diff options
Diffstat (limited to 'src/backend/access/transam/xlogreader.c')
| -rw-r--r-- | src/backend/access/transam/xlogreader.c | 1545 |
1 files changed, 445 insertions, 1100 deletions
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c index 4277e92d7c9..42738eb940c 100644 --- a/src/backend/access/transam/xlogreader.c +++ b/src/backend/access/transam/xlogreader.c @@ -36,14 +36,11 @@ static void report_invalid_record(XLogReaderState *state, const char *fmt,...) pg_attribute_printf(2, 3); static bool allocate_recordbuf(XLogReaderState *state, uint32 reclength); -static bool XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr, - int reqLen, bool header_inclusive); -size_t DecodeXLogRecordRequiredSpace(size_t xl_tot_len); -static XLogReadRecordResult XLogDecodeOneRecord(XLogReaderState *state, - bool allow_oversized); +static int ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, + int reqLen); static void XLogReaderInvalReadState(XLogReaderState *state); static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr, - XLogRecPtr PrevRecPtr, XLogRecord *record); + XLogRecPtr PrevRecPtr, XLogRecord *record, bool randAccess); static bool ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr); static void ResetDecoder(XLogReaderState *state); @@ -53,8 +50,6 @@ static void WALOpenSegmentInit(WALOpenSegment *seg, WALSegmentContext *segcxt, /* size of the buffer allocated for error message. */ #define MAX_ERRORMSG_LEN 1000 -#define DEFAULT_DECODE_BUFFER_SIZE 0x10000 - /* * Construct a string in state->errormsg_buf explaining what's wrong with * the current record being read. @@ -69,8 +64,6 @@ report_invalid_record(XLogReaderState *state, const char *fmt,...) va_start(args, fmt); vsnprintf(state->errormsg_buf, MAX_ERRORMSG_LEN, fmt, args); va_end(args); - - state->errormsg_deferred = true; } /* @@ -80,7 +73,7 @@ report_invalid_record(XLogReaderState *state, const char *fmt,...) */ XLogReaderState * XLogReaderAllocate(int wal_segment_size, const char *waldir, - WALSegmentCleanupCB cleanup_cb) + XLogReaderRoutine *routine, void *private_data) { XLogReaderState *state; @@ -91,7 +84,9 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir, return NULL; /* initialize caller-provided support functions */ - state->cleanup_cb = cleanup_cb; + state->routine = *routine; + + state->max_block_id = -1; /* * Permanently allocate readBuf. We do it this way, rather than just @@ -112,7 +107,9 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir, WALOpenSegmentInit(&state->seg, &state->segcxt, wal_segment_size, waldir); - /* ReadRecPtr, EndRecPtr, reqLen and readLen initialized to zeroes above */ + /* system_identifier initialized to zeroes above */ + state->private_data = private_data; + /* ReadRecPtr, EndRecPtr and readLen initialized to zeroes above */ state->errormsg_buf = palloc_extended(MAX_ERRORMSG_LEN + 1, MCXT_ALLOC_NO_OOM); if (!state->errormsg_buf) @@ -141,11 +138,18 @@ XLogReaderAllocate(int wal_segment_size, const char *waldir, void XLogReaderFree(XLogReaderState *state) { - if (state->seg.ws_file >= 0) - state->cleanup_cb(state); + int block_id; - if (state->decode_buffer && state->free_decode_buffer) - pfree(state->decode_buffer); + if (state->seg.ws_file != -1) + state->routine.segment_close(state); + + for (block_id = 0; block_id <= XLR_MAX_BLOCK_ID; block_id++) + { + if (state->blocks[block_id].data) + pfree(state->blocks[block_id].data); + } + if (state->main_data) + pfree(state->main_data); pfree(state->errormsg_buf); if (state->readRecordBuf) @@ -155,22 +159,6 @@ XLogReaderFree(XLogReaderState *state) } /* - * Set the size of the decoding buffer. A pointer to a caller supplied memory - * region may also be passed in, in which case non-oversized records will be - * decoded there. - */ -void -XLogReaderSetDecodeBuffer(XLogReaderState *state, void *buffer, size_t size) -{ - Assert(state->decode_buffer == NULL); - - state->decode_buffer = buffer; - state->decode_buffer_size = size; - state->decode_buffer_head = buffer; - state->decode_buffer_tail = buffer; -} - -/* * Allocate readRecordBuf to fit a record of at least the given length. * Returns true if successful, false if out of memory. * @@ -257,799 +245,290 @@ XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr) /* Begin at the passed-in record pointer. */ state->EndRecPtr = RecPtr; - state->NextRecPtr = RecPtr; state->ReadRecPtr = InvalidXLogRecPtr; - state->DecodeRecPtr = InvalidXLogRecPtr; - state->readRecordState = XLREAD_NEXT_RECORD; } /* - * See if we can release the last record that was returned by - * XLogReadRecord(), to free up space. + * Attempt to read an XLOG record. + * + * XLogBeginRead() or XLogFindNextRecord() must be called before the first call + * to XLogReadRecord(). + * + * If the page_read callback fails to read the requested data, NULL is + * returned. The callback is expected to have reported the error; errormsg + * is set to NULL. + * + * If the reading fails for some other reason, NULL is also returned, and + * *errormsg is set to a string with details of the failure. + * + * The returned pointer (or *errormsg) points to an internal buffer that's + * valid until the next call to XLogReadRecord. */ -static void -XLogReleasePreviousRecord(XLogReaderState *state) +XLogRecord * +XLogReadRecord(XLogReaderState *state, char **errormsg) { - DecodedXLogRecord *record; + XLogRecPtr RecPtr; + XLogRecord *record; + XLogRecPtr targetPagePtr; + bool randAccess; + uint32 len, + total_len; + uint32 targetRecOff; + uint32 pageHeaderSize; + bool gotheader; + int readOff; /* - * Remove it from the decoded record queue. It must be the oldest - * item decoded, decode_queue_tail. + * randAccess indicates whether to verify the previous-record pointer of + * the record we're reading. We only do this if we're reading + * sequentially, which is what we initially assume. */ - record = state->record; - Assert(record == state->decode_queue_tail); - state->record = NULL; - state->decode_queue_tail = record->next; + randAccess = false; - /* It might also be the newest item decoded, decode_queue_head. */ - if (state->decode_queue_head == record) - state->decode_queue_head = NULL; + /* reset error state */ + *errormsg = NULL; + state->errormsg_buf[0] = '\0'; - /* Release the space. */ - if (unlikely(record->oversized)) - { - /* It's not in the the decode buffer, so free it to release space. */ - pfree(record); - } - else + ResetDecoder(state); + + RecPtr = state->EndRecPtr; + + if (state->ReadRecPtr != InvalidXLogRecPtr) { - /* It must be the tail record in the decode buffer. */ - Assert(state->decode_buffer_tail == (char *) record); + /* read the record after the one we just read */ /* - * We need to update tail to point to the next record that is in the - * decode buffer, if any, being careful to skip oversized ones - * (they're not in the decode buffer). + * EndRecPtr is pointing to end+1 of the previous WAL record. If + * we're at a page boundary, no more records can fit on the current + * page. We must skip over the page header, but we can't do that until + * we've read in the page, since the header size is variable. */ - record = record->next; - while (unlikely(record && record->oversized)) - record = record->next; - - if (record) - { - /* Adjust tail to release space up to the next record. */ - state->decode_buffer_tail = (char *) record; - } - else if (state->decoding && !state->decoding->oversized) - { - /* - * We're releasing the last fully decoded record in - * XLogReadRecord(), but some time earlier we partially decoded a - * record in XLogReadAhead() and were unable to complete the job. - * We'll set the buffer head and tail to point to the record we - * started working on, so that we can continue (perhaps from a - * different source). - */ - state->decode_buffer_tail = (char *) state->decoding; - state->decode_buffer_head = (char *) state->decoding; - } - else - { - /* - * Otherwise we might as well just reset head and tail to the - * start of the buffer space, because we're empty. This means - * we'll keep overwriting the same piece of memory if we're not - * doing any prefetching. - */ - state->decode_buffer_tail = state->decode_buffer; - state->decode_buffer_head = state->decode_buffer; - } } -} - -/* - * Similar to XLogNextRecord(), but this traditional interface is for code - * that just wants the header, not the decoded record. Callers can access the - * decoded record through the XLogRecGetXXX() macros. - */ -XLogReadRecordResult -XLogReadRecord(XLogReaderState *state, XLogRecord **record, char **errormsg) -{ - XLogReadRecordResult result; - DecodedXLogRecord *decoded; - - /* Consume the next decoded record. */ - result = XLogNextRecord(state, &decoded, errormsg); - if (result == XLREAD_SUCCESS) + else { /* - * The traditional interface just returns the header, not the decoded - * record. The caller will access the decoded record through the - * XLogRecGetXXX() macros. + * Caller supplied a position to start at. + * + * In this case, EndRecPtr should already be pointing to a valid + * record starting position. */ - *record = &decoded->header; + Assert(XRecOffIsValid(RecPtr)); + randAccess = true; } - else - *record = NULL; - return result; -} -/* - * Consume the next record. XLogBeginRead() or XLogFindNextRecord() must be - * called before the first call to XLogNextRecord(). - * - * This function may return XLREAD_NEED_DATA several times before returning a - * result record. The caller shall read in some new data then call this - * function again with the same parameters. - * - * When a record is successfully read, returns XLREAD_SUCCESS with result - * record being stored in *record. Otherwise *record is set to NULL. - * - * Returns XLREAD_NEED_DATA if more data is needed to finish decoding the - * current record. In that case, state->readPagePtr and state->reqLen inform - * the desired position and minimum length of data needed. The caller shall - * read in the requested data and set state->readBuf to point to a buffer - * containing it. The caller must also set state->seg->ws_tli and - * state->readLen to indicate the timeline that it was read from, and the - * length of data that is now available (which must be >= given reqLen), - * respectively. - * - * Returns XLREAD_FULL if allow_oversized is true, and no space is available. - * This is intended for readahead. - * - * If invalid data is encountered, returns XLREAD_FAIL with *record being set - * to NULL. *errormsg is set to a string with details of the failure. The - * returned pointer (or *errormsg) points to an internal buffer that's valid - * until the next call to XLogReadRecord. - * - */ -XLogReadRecordResult -XLogNextRecord(XLogReaderState *state, - DecodedXLogRecord **record, - char **errormsg) -{ - /* Release the space occupied by the last record we returned. */ - if (state->record) - XLogReleasePreviousRecord(state); + state->currRecPtr = RecPtr; - for (;;) - { - XLogReadRecordResult result; - - /* We can now return the oldest item in the queue, if there is one. */ - if (state->decode_queue_tail) - { - /* - * Record this as the most recent record returned, so that we'll - * release it next time. This also exposes it to the - * XLogRecXXX(decoder) macros, which pass in the decoder rather - * than the record for historical reasons. - */ - state->record = state->decode_queue_tail; - - /* - * It should be immediately after the last the record returned by - * XLogReadRecord(), or at the position set by XLogBeginRead() if - * XLogReadRecord() hasn't been called yet. It may be after a - * page header, though. - */ - Assert(state->record->lsn == state->EndRecPtr || - (state->EndRecPtr % XLOG_BLCKSZ == 0 && - (state->record->lsn == state->EndRecPtr + SizeOfXLogShortPHD || - state->record->lsn == state->EndRecPtr + SizeOfXLogLongPHD))); - - /* - * Set ReadRecPtr and EndRecPtr to correspond to that - * record. - * - * Calling code could access these through the returned decoded - * record, but for now we'll update them directly here, for the - * benefit of all the existing code that accesses these variables - * directly. - */ - state->ReadRecPtr = state->record->lsn; - state->EndRecPtr = state->record->next_lsn; + targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ); + targetRecOff = RecPtr % XLOG_BLCKSZ; - *errormsg = NULL; - *record = state->record; - - return XLREAD_SUCCESS; - } - else if (state->errormsg_deferred) - { - /* - * If we've run out of records, but we have a deferred error, now - * is the time to report it. - */ - state->errormsg_deferred = false; - if (state->errormsg_buf[0] != '\0') - *errormsg = state->errormsg_buf; - else - *errormsg = NULL; - *record = NULL; - state->EndRecPtr = state->DecodeRecPtr; - - return XLREAD_FAIL; - } + /* + * Read the page containing the record into state->readBuf. Request enough + * byte to cover the whole record header, or at least the part of it that + * fits on the same page. + */ + readOff = ReadPageInternal(state, targetPagePtr, + Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ)); + if (readOff < 0) + goto err; - /* We need to get a decoded record into our queue first. */ - result = XLogDecodeOneRecord(state, true /* allow_oversized */ ); - switch(result) - { - case XLREAD_NEED_DATA: - *errormsg = NULL; - *record = NULL; - return result; - case XLREAD_SUCCESS: - Assert(state->decode_queue_tail != NULL); - break; - case XLREAD_FULL: - /* Not expected because we passed allow_oversized = true */ - Assert(false); - break; - case XLREAD_FAIL: - /* - * If that produced neither a queued record nor a queued error, - * then we're at the end (for example, archive recovery with no - * more files available). - */ - Assert(state->decode_queue_tail == NULL); - if (!state->errormsg_deferred) - { - state->EndRecPtr = state->DecodeRecPtr; - *errormsg = NULL; - *record = NULL; - return result; - } - break; - } + /* + * ReadPageInternal always returns at least the page header, so we can + * examine it now. + */ + pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf); + if (targetRecOff == 0) + { + /* + * At page start, so skip over page header. + */ + RecPtr += pageHeaderSize; + targetRecOff = pageHeaderSize; } - - /* unreachable */ - return XLREAD_FAIL; -} - -/* - * Try to decode the next available record. The next record will also be - * returned to XLogRecordRead(). - * - * In addition to the values that XLogReadRecord() can return, XLogReadAhead() - * can also return XLREAD_FULL to indicate that further readahead is not - * possible yet due to lack of space. - */ -XLogReadRecordResult -XLogReadAhead(XLogReaderState *state, DecodedXLogRecord **record, char **errormsg) -{ - XLogReadRecordResult result; - - /* We stop trying after encountering an error. */ - if (unlikely(state->errormsg_deferred)) + else if (targetRecOff < pageHeaderSize) { - /* We only report the error message the first time, see below. */ - *errormsg = NULL; - return XLREAD_FAIL; + report_invalid_record(state, "invalid record offset at %X/%X", + LSN_FORMAT_ARGS(RecPtr)); + goto err; } - /* - * Try to decode one more record, if we have space. Pass allow_oversized - * = false, so that this call returns fast if the decode buffer is full. - */ - result = XLogDecodeOneRecord(state, false); - switch (result) + if ((((XLogPageHeader) state->readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) && + targetRecOff == pageHeaderSize) { - case XLREAD_SUCCESS: - /* New record at head of decode record queue. */ - Assert(state->decode_queue_head != NULL); - *record = state->decode_queue_head; - return result; - case XLREAD_FULL: - /* No space in circular decode buffer. */ - return result; - case XLREAD_NEED_DATA: - /* The caller needs to insert more data. */ - return result; - case XLREAD_FAIL: - /* Report the error. XLogReadRecord() will also report it. */ - Assert(state->errormsg_deferred); - if (state->errormsg_buf[0] != '\0') - *errormsg = state->errormsg_buf; - return result; + report_invalid_record(state, "contrecord is requested by %X/%X", + LSN_FORMAT_ARGS(RecPtr)); + goto err; } - /* Unreachable. */ - return XLREAD_FAIL; -} + /* ReadPageInternal has verified the page header */ + Assert(pageHeaderSize <= readOff); -/* - * Allocate space for a decoded record. The only member of the returned - * object that is initialized is the 'oversized' flag, indicating that the - * decoded record wouldn't fit in the decode buffer and must eventually be - * freed explicitly. - * - * Return NULL if there is no space in the decode buffer and allow_oversized - * is false, or if memory allocation fails for an oversized buffer. - */ -static DecodedXLogRecord * -XLogReadRecordAlloc(XLogReaderState *state, size_t xl_tot_len, bool allow_oversized) -{ - size_t required_space = DecodeXLogRecordRequiredSpace(xl_tot_len); - DecodedXLogRecord *decoded = NULL; + /* + * Read the record length. + * + * NB: Even though we use an XLogRecord pointer here, the whole record + * header might not fit on this page. xl_tot_len is the first field of the + * struct, so it must be on this page (the records are MAXALIGNed), but we + * cannot access any other fields until we've verified that we got the + * whole header. + */ + record = (XLogRecord *) (state->readBuf + RecPtr % XLOG_BLCKSZ); + total_len = record->xl_tot_len; - /* Allocate a circular decode buffer if we don't have one already. */ - if (unlikely(state->decode_buffer == NULL)) - { - if (state->decode_buffer_size == 0) - state->decode_buffer_size = DEFAULT_DECODE_BUFFER_SIZE; - state->decode_buffer = palloc(state->decode_buffer_size); - state->decode_buffer_head = state->decode_buffer; - state->decode_buffer_tail = state->decode_buffer; - state->free_decode_buffer = true; - } - if (state->decode_buffer_head >= state->decode_buffer_tail) + /* + * If the whole record header is on this page, validate it immediately. + * Otherwise do just a basic sanity check on xl_tot_len, and validate the + * rest of the header after reading it from the next page. The xl_tot_len + * check is necessary here to ensure that we enter the "Need to reassemble + * record" code path below; otherwise we might fail to apply + * ValidXLogRecordHeader at all. + */ + if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord) { - /* Empty, or head is to the right of tail. */ - if (state->decode_buffer_head + required_space <= - state->decode_buffer + state->decode_buffer_size) - { - /* There is space between head and end. */ - decoded = (DecodedXLogRecord *) state->decode_buffer_head; - decoded->oversized = false; - return decoded; - } - else if (state->decode_buffer + required_space < - state->decode_buffer_tail) - { - /* There is space between start and tail. */ - decoded = (DecodedXLogRecord *) state->decode_buffer; - decoded->oversized = false; - return decoded; - } + if (!ValidXLogRecordHeader(state, RecPtr, state->ReadRecPtr, record, + randAccess)) + goto err; + gotheader = true; } else { - /* Head is to the left of tail. */ - if (state->decode_buffer_head + required_space < - state->decode_buffer_tail) + /* XXX: more validation should be done here */ + if (total_len < SizeOfXLogRecord) { - /* There is space between head and tail. */ - decoded = (DecodedXLogRecord *) state->decode_buffer_head; - decoded->oversized = false; - return decoded; + report_invalid_record(state, + "invalid record length at %X/%X: wanted %u, got %u", + LSN_FORMAT_ARGS(RecPtr), + (uint32) SizeOfXLogRecord, total_len); + goto err; } + gotheader = false; } - /* Not enough space in the decode buffer. Are we allowed to allocate? */ - if (allow_oversized) + len = XLOG_BLCKSZ - RecPtr % XLOG_BLCKSZ; + if (total_len > len) { - decoded = palloc_extended(required_space, MCXT_ALLOC_NO_OOM); - if (decoded == NULL) - return NULL; - decoded->oversized = true; - return decoded; - } + /* Need to reassemble record */ + char *contdata; + XLogPageHeader pageHeader; + char *buffer; + uint32 gotlen; - return decoded; -} - -/* - * Try to read and decode the next record and add it to the head of the - * decoded record queue. If 'allow_oversized' is false, then XLREAD_FULL can - * be returned to indicate the decoding buffer is full. XLogBeginRead() or - * XLogFindNextRecord() must be called before the first call to - * XLogReadRecord(). - * - * This function runs a state machine consisting of the following states. - * - * XLREAD_NEXT_RECORD: - * The initial state. If called with a valid XLogRecPtr, try to read a - * record at that position. If invalid RecPtr is given try to read a record - * just after the last one read. The next state is XLREAD_TOT_LEN. - * - * XLREAD_TOT_LEN: - * Examining record header. Ends after reading record length. - * recordRemainLen and recordGotLen are initialized. The next state is - * XLREAD_FIRST_FRAGMENT. - * - * XLREAD_FIRST_FRAGMENT: - * Reading the first fragment. Goes to XLREAD_NEXT_RECORD if that's all or - * XLREAD_CONTINUATION if we need more data. - - * XLREAD_CONTINUATION: - * Reading continuation of record. If the whole record is now decoded, goes - * to XLREAD_NEXT_RECORD. During this state, recordRemainLen indicates how - * much is left. - * - * If invalid data is found in any state, the state machine stays at the - * current state. This behavior allows us to continue reading a record - * after switching to a different source, during streaming replication. - */ -static XLogReadRecordResult -XLogDecodeOneRecord(XLogReaderState *state, bool allow_oversized) -{ - XLogRecord *record; - char *errormsg; /* not used */ - XLogRecord *prec; - - /* reset error state */ - state->errormsg_buf[0] = '\0'; - record = NULL; + /* + * Enlarge readRecordBuf as needed. + */ + if (total_len > state->readRecordBufSize && + !allocate_recordbuf(state, total_len)) + { + /* We treat this as a "bogus data" condition */ + report_invalid_record(state, "record length %u at %X/%X too long", + total_len, LSN_FORMAT_ARGS(RecPtr)); + goto err; + } - switch (state->readRecordState) - { - case XLREAD_NEXT_RECORD: - Assert(!state->decoding); + /* Copy the first fragment of the record from the first page. */ + memcpy(state->readRecordBuf, + state->readBuf + RecPtr % XLOG_BLCKSZ, len); + buffer = state->readRecordBuf + len; + gotlen = len; - if (state->DecodeRecPtr != InvalidXLogRecPtr) - { - /* read the record after the one we just read */ + do + { + /* Calculate pointer to beginning of next page */ + targetPagePtr += XLOG_BLCKSZ; - /* - * NextRecPtr is pointing to end+1 of the previous WAL record. - * If we're at a page boundary, no more records can fit on the - * current page. We must skip over the page header, but we - * can't do that until we've read in the page, since the - * header size is variable. - */ - state->PrevRecPtr = state->DecodeRecPtr; - state->DecodeRecPtr = state->NextRecPtr; - } - else - { - /* - * Caller supplied a position to start at. - * - * In this case, EndRecPtr should already be pointing to a - * valid record starting position. - */ - Assert(XRecOffIsValid(state->NextRecPtr)); - state->DecodeRecPtr = state->NextRecPtr; + /* Wait for the next page to become available */ + readOff = ReadPageInternal(state, targetPagePtr, + Min(total_len - gotlen + SizeOfXLogShortPHD, + XLOG_BLCKSZ)); - /* - * We cannot verify the previous-record pointer when we're - * seeking to a particular record. Reset PrevRecPtr so that we - * won't try doing that. - */ - state->PrevRecPtr = InvalidXLogRecPtr; - } + if (readOff < 0) + goto err; - state->record_verified = false; - state->readRecordState = XLREAD_TOT_LEN; - /* fall through */ + Assert(SizeOfXLogShortPHD <= readOff); - case XLREAD_TOT_LEN: + /* Check that the continuation on next page looks valid */ + pageHeader = (XLogPageHeader) state->readBuf; + if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD)) { - uint32 total_len; - uint32 pageHeaderSize; - XLogRecPtr targetPagePtr; - uint32 targetRecOff; - XLogPageHeader pageHeader; - - Assert(!state->decoding); - - targetPagePtr = - state->DecodeRecPtr - (state->DecodeRecPtr % XLOG_BLCKSZ); - targetRecOff = state->DecodeRecPtr % XLOG_BLCKSZ; - - /* - * Check if we have enough data. For the first record in the - * page, the requesting length doesn't contain page header. - */ - if (XLogNeedData(state, targetPagePtr, - Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ), - targetRecOff != 0)) - return XLREAD_NEED_DATA; - - /* error out if caller supplied bogus page */ - if (!state->page_verified) - goto err; - - /* examine page header now. */ - pageHeaderSize = - XLogPageHeaderSize((XLogPageHeader) state->readBuf); - if (targetRecOff == 0) - { - /* At page start, so skip over page header. */ - state->DecodeRecPtr += pageHeaderSize; - targetRecOff = pageHeaderSize; - } - else if (targetRecOff < pageHeaderSize) - { - report_invalid_record(state, "invalid record offset at %X/%X", - LSN_FORMAT_ARGS(state->DecodeRecPtr)); - goto err; - } - - pageHeader = (XLogPageHeader) state->readBuf; - if ((pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD) && - targetRecOff == pageHeaderSize) - { - report_invalid_record(state, "contrecord is requested by %X/%X", - LSN_FORMAT_ARGS(state->DecodeRecPtr)); - goto err; - } - - /* XLogNeedData has verified the page header */ - Assert(pageHeaderSize <= state->readLen); - - /* - * Read the record length. - * - * NB: Even though we use an XLogRecord pointer here, the - * whole record header might not fit on this page. xl_tot_len - * is the first field of the struct, so it must be on this - * page (the records are MAXALIGNed), but we cannot access any - * other fields until we've verified that we got the whole - * header. - */ - prec = (XLogRecord *) (state->readBuf + - state->DecodeRecPtr % XLOG_BLCKSZ); - total_len = prec->xl_tot_len; - - /* Find space to decode this record. */ - Assert(state->decoding == NULL); - state->decoding = XLogReadRecordAlloc(state, total_len, - allow_oversized); - if (state->decoding == NULL) - { - /* - * We couldn't get space. If allow_oversized was true, - * then palloc() must have failed. Otherwise, report that - * our decoding buffer is full. This means that weare - * trying to read too far ahead. - */ - if (allow_oversized) - goto err; - return XLREAD_FULL; - } - - /* - * If the whole record header is on this page, validate it - * immediately. Otherwise do just a basic sanity check on - * xl_tot_len, and validate the rest of the header after - * reading it from the next page. The xl_tot_len check is - * necessary here to ensure that we enter the - * XLREAD_CONTINUATION state below; otherwise we might fail to - * apply ValidXLogRecordHeader at all. - */ - if (targetRecOff <= XLOG_BLCKSZ - SizeOfXLogRecord) - { - if (!ValidXLogRecordHeader(state, state->DecodeRecPtr, - state->PrevRecPtr, prec)) - goto err; - - state->record_verified = true; - } - else - { - /* XXX: more validation should be done here */ - if (total_len < SizeOfXLogRecord) - { - report_invalid_record(state, - "invalid record length at %X/%X: wanted %u, got %u", - LSN_FORMAT_ARGS(state->DecodeRecPtr), - (uint32) SizeOfXLogRecord, total_len); - goto err; - } - } - - /* - * Wait for the rest of the record, or the part of the record - * that fit on the first page if crossed a page boundary, to - * become available. - */ - state->recordGotLen = 0; - state->recordRemainLen = total_len; - state->readRecordState = XLREAD_FIRST_FRAGMENT; + report_invalid_record(state, + "there is no contrecord flag at %X/%X", + LSN_FORMAT_ARGS(RecPtr)); + goto err; } - /* fall through */ - case XLREAD_FIRST_FRAGMENT: + /* + * Cross-check that xlp_rem_len agrees with how much of the record + * we expect there to be left. + */ + if (pageHeader->xlp_rem_len == 0 || + total_len != (pageHeader->xlp_rem_len + gotlen)) { - uint32 total_len = state->recordRemainLen; - uint32 request_len; - uint32 record_len; - XLogRecPtr targetPagePtr; - uint32 targetRecOff; - - Assert(state->decoding); - - /* - * Wait for the rest of the record on the first page to become - * available - */ - targetPagePtr = - state->DecodeRecPtr - (state->DecodeRecPtr % XLOG_BLCKSZ); - targetRecOff = state->DecodeRecPtr % XLOG_BLCKSZ; - - request_len = Min(targetRecOff + total_len, XLOG_BLCKSZ); - record_len = request_len - targetRecOff; - - /* ReadRecPtr contains page header */ - Assert(targetRecOff != 0); - if (XLogNeedData(state, targetPagePtr, request_len, true)) - return XLREAD_NEED_DATA; - - /* error out if caller supplied bogus page */ - if (!state->page_verified) - goto err; - - prec = (XLogRecord *) (state->readBuf + targetRecOff); - - /* validate record header if not yet */ - if (!state->record_verified && record_len >= SizeOfXLogRecord) - { - if (!ValidXLogRecordHeader(state, state->DecodeRecPtr, - state->PrevRecPtr, prec)) - goto err; - - state->record_verified = true; - } - + report_invalid_record(state, + "invalid contrecord length %u (expected %lld) at %X/%X", + pageHeader->xlp_rem_len, + ((long long) total_len) - gotlen, + LSN_FORMAT_ARGS(RecPtr)); + goto err; + } - if (total_len == record_len) - { - /* Record does not cross a page boundary */ - Assert(state->record_verified); + /* Append the continuation from this page to the buffer */ + pageHeaderSize = XLogPageHeaderSize(pageHeader); - if (!ValidXLogRecord(state, prec, state->DecodeRecPtr)) - goto err; + if (readOff < pageHeaderSize) + readOff = ReadPageInternal(state, targetPagePtr, + pageHeaderSize); - state->record_verified = true; /* to be tidy */ + Assert(pageHeaderSize <= readOff); - /* We already checked the header earlier */ - state->NextRecPtr = state->DecodeRecPtr + MAXALIGN(record_len); + contdata = (char *) state->readBuf + pageHeaderSize; + len = XLOG_BLCKSZ - pageHeaderSize; + if (pageHeader->xlp_rem_len < len) + len = pageHeader->xlp_rem_len; - record = prec; - state->readRecordState = XLREAD_NEXT_RECORD; - break; - } + if (readOff < pageHeaderSize + len) + readOff = ReadPageInternal(state, targetPagePtr, + pageHeaderSize + len); - /* - * The record continues on the next page. Need to reassemble - * record - */ - Assert(total_len > record_len); + memcpy(buffer, (char *) contdata, len); + buffer += len; + gotlen += len; - /* Enlarge readRecordBuf as needed. */ - if (total_len > state->readRecordBufSize && - !allocate_recordbuf(state, total_len)) - { - /* We treat this as a "bogus data" condition */ - report_invalid_record(state, - "record length %u at %X/%X too long", - total_len, - LSN_FORMAT_ARGS(state->DecodeRecPtr)); + /* If we just reassembled the record header, validate it. */ + if (!gotheader) + { + record = (XLogRecord *) state->readRecordBuf; + if (!ValidXLogRecordHeader(state, RecPtr, state->ReadRecPtr, + record, randAccess)) goto err; - } - - /* Copy the first fragment of the record from the first page. */ - memcpy(state->readRecordBuf, state->readBuf + targetRecOff, - record_len); - state->recordGotLen += record_len; - state->recordRemainLen -= record_len; - - /* Calculate pointer to beginning of next page */ - state->recordContRecPtr = state->DecodeRecPtr + record_len; - Assert(state->recordContRecPtr % XLOG_BLCKSZ == 0); - - state->readRecordState = XLREAD_CONTINUATION; + gotheader = true; } - /* fall through */ + } while (gotlen < total_len); - case XLREAD_CONTINUATION: - { - XLogPageHeader pageHeader = NULL; - uint32 pageHeaderSize; - XLogRecPtr targetPagePtr = InvalidXLogRecPtr; + Assert(gotheader); - /* - * we enter this state only if we haven't read the whole - * record. - */ - Assert(state->decoding); - Assert(state->recordRemainLen > 0); - - while (state->recordRemainLen > 0) - { - char *contdata; - uint32 request_len PG_USED_FOR_ASSERTS_ONLY; - uint32 record_len; - - /* Wait for the next page to become available */ - targetPagePtr = state->recordContRecPtr; - - /* this request contains page header */ - Assert(targetPagePtr != 0); - if (XLogNeedData(state, targetPagePtr, - Min(state->recordRemainLen, XLOG_BLCKSZ), - false)) - return XLREAD_NEED_DATA; - - if (!state->page_verified) - goto err_continue; - - Assert(SizeOfXLogShortPHD <= state->readLen); - - /* Check that the continuation on next page looks valid */ - pageHeader = (XLogPageHeader) state->readBuf; - if (!(pageHeader->xlp_info & XLP_FIRST_IS_CONTRECORD)) - { - report_invalid_record( - state, - "there is no contrecord flag at %X/%X reading %X/%X", - LSN_FORMAT_ARGS(state->recordContRecPtr), - LSN_FORMAT_ARGS(state->DecodeRecPtr)); - goto err; - } - - /* - * Cross-check that xlp_rem_len agrees with how much of - * the record we expect there to be left. - */ - if (pageHeader->xlp_rem_len == 0 || - pageHeader->xlp_rem_len != state->recordRemainLen) - { - report_invalid_record( - state, - "invalid contrecord length %u at %X/%X reading %X/%X, expected %u", - pageHeader->xlp_rem_len, - LSN_FORMAT_ARGS(state->recordContRecPtr), - LSN_FORMAT_ARGS(state->DecodeRecPtr), - state->recordRemainLen); - goto err; - } - - /* Append the continuation from this page to the buffer */ - pageHeaderSize = XLogPageHeaderSize(pageHeader); - - /* - * XLogNeedData should have ensured that the whole page - * header was read - */ - Assert(pageHeaderSize <= state->readLen); - - contdata = (char *) state->readBuf + pageHeaderSize; - record_len = XLOG_BLCKSZ - pageHeaderSize; - if (pageHeader->xlp_rem_len < record_len) - record_len = pageHeader->xlp_rem_len; - - request_len = record_len + pageHeaderSize; - - /* - * XLogNeedData should have ensured all needed data was - * read - */ - Assert(request_len <= state->readLen); - - memcpy(state->readRecordBuf + state->recordGotLen, - (char *) contdata, record_len); - state->recordGotLen += record_len; - state->recordRemainLen -= record_len; - - /* If we just reassembled the record header, validate it. */ - if (!state->record_verified) - { - Assert(state->recordGotLen >= SizeOfXLogRecord); - if (!ValidXLogRecordHeader(state, state->DecodeRecPtr, - state->PrevRecPtr, - (XLogRecord *) state->readRecordBuf)) - goto err; - - state->record_verified = true; - } - - /* - * Calculate pointer to beginning of next page, and - * continue - */ - state->recordContRecPtr += XLOG_BLCKSZ; - } + record = (XLogRecord *) state->readRecordBuf; + if (!ValidXLogRecord(state, record, RecPtr)) + goto err; - /* targetPagePtr is pointing the last-read page here */ - prec = (XLogRecord *) state->readRecordBuf; - if (!ValidXLogRecord(state, prec, state->DecodeRecPtr)) - goto err; + pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf); + state->ReadRecPtr = RecPtr; + state->EndRecPtr = targetPagePtr + pageHeaderSize + + MAXALIGN(pageHeader->xlp_rem_len); + } + else + { + /* Wait for the record data to become available */ + readOff = ReadPageInternal(state, targetPagePtr, + Min(targetRecOff + total_len, XLOG_BLCKSZ)); + if (readOff < 0) + goto err; - pageHeaderSize = - XLogPageHeaderSize((XLogPageHeader) state->readBuf); - state->NextRecPtr = targetPagePtr + pageHeaderSize - + MAXALIGN(pageHeader->xlp_rem_len); + /* Record does not cross a page boundary */ + if (!ValidXLogRecord(state, record, RecPtr)) + goto err; - record = prec; - state->readRecordState = XLREAD_NEXT_RECORD; + state->EndRecPtr = RecPtr + MAXALIGN(total_len); - break; - } + state->ReadRecPtr = RecPtr; } /* @@ -1059,195 +538,133 @@ XLogDecodeOneRecord(XLogReaderState *state, bool allow_oversized) (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH) { /* Pretend it extends to end of segment */ - state->NextRecPtr += state->segcxt.ws_segsize - 1; - state->NextRecPtr -= XLogSegmentOffset(state->NextRecPtr, state->segcxt.ws_segsize); + state->EndRecPtr += state->segcxt.ws_segsize - 1; + state->EndRecPtr -= XLogSegmentOffset(state->EndRecPtr, state->segcxt.ws_segsize); } - Assert(!record || state->readLen >= 0); - if (DecodeXLogRecord(state, state->decoding, record, state->DecodeRecPtr, &errormsg)) - { - /* Record the location of the next record. */ - state->decoding->next_lsn = state->NextRecPtr; - - /* - * If it's in the decode buffer (not an "oversized" record allocated - * with palloc()), mark the decode buffer space as occupied. - */ - if (!state->decoding->oversized) - { - /* The new decode buffer head must be MAXALIGNed. */ - Assert(state->decoding->size == MAXALIGN(state->decoding->size)); - if ((char *) state->decoding == state->decode_buffer) - state->decode_buffer_head = state->decode_buffer + - state->decoding->size; - else - state->decode_buffer_head += state->decoding->size; - } - - /* Insert it into the queue of decoded records. */ - Assert(state->decode_queue_head != state->decoding); - if (state->decode_queue_head) - state->decode_queue_head->next = state->decoding; - state->decode_queue_head = state->decoding; - if (!state->decode_queue_tail) - state->decode_queue_tail = state->decoding; - state->decoding = NULL; - - return XLREAD_SUCCESS; - } + if (DecodeXLogRecord(state, record, errormsg)) + return record; + else + return NULL; err: - if (state->decoding && state->decoding->oversized) - pfree(state->decoding); - state->decoding = NULL; -err_continue: /* - * Invalidate the read page. We might read from a different source after + * Invalidate the read state. We might read from a different source after * failure. */ XLogReaderInvalReadState(state); - /* - * If an error was written to errmsg_buf, it'll be returned to the caller - * of XLogReadRecord() after all successfully decoded records from the - * read queue. - */ + if (state->errormsg_buf[0] != '\0') + *errormsg = state->errormsg_buf; - return XLREAD_FAIL; + return NULL; } /* - * Checks that an xlog page loaded in state->readBuf is including at least - * [pageptr, reqLen] and the page is valid. header_inclusive indicates that - * reqLen is calculated including page header length. - * - * Returns false if the buffer already contains the requested data, or found - * error. state->page_verified is set to true for the former and false for the - * latter. + * Read a single xlog page including at least [pageptr, reqLen] of valid data + * via the page_read() callback. * - * Otherwise returns true and requests data loaded onto state->readBuf by - * state->readPagePtr and state->readLen. The caller shall call this function - * again after filling the buffer at least with that portion of data and set - * state->readLen to the length of actually loaded data. + * Returns -1 if the required page cannot be read for some reason; errormsg_buf + * is set in that case (unless the error occurs in the page_read callback). * - * If header_inclusive is false, corrects reqLen internally by adding the - * actual page header length and may request caller for new data. + * We fetch the page from a reader-local cache if we know we have the required + * data and if there hasn't been any error since caching the data. */ -static bool -XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr, int reqLen, - bool header_inclusive) +static int +ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen) { + int readLen; uint32 targetPageOff; XLogSegNo targetSegNo; - uint32 addLen = 0; + XLogPageHeader hdr; - /* Some data is loaded, but page header is not verified yet. */ - if (!state->page_verified && - !XLogRecPtrIsInvalid(state->readPagePtr) && state->readLen >= 0) - { - uint32 pageHeaderSize; - - /* just loaded new data so needs to verify page header */ - - /* The caller must have loaded at least page header */ - Assert(state->readLen >= SizeOfXLogShortPHD); + Assert((pageptr % XLOG_BLCKSZ) == 0); - /* - * We have enough data to check the header length. Recheck the loaded - * length against the actual header length. - */ - pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf); + XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize); + targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize); - /* Request more data if we don't have the full header. */ - if (state->readLen < pageHeaderSize) - { - state->reqLen = pageHeaderSize; - return true; - } + /* check whether we have all the requested data already */ + if (targetSegNo == state->seg.ws_segno && + targetPageOff == state->segoff && reqLen <= state->readLen) + return state->readLen; - /* Now that we know we have the full header, validate it. */ - if (!XLogReaderValidatePageHeader(state, state->readPagePtr, - (char *) state->readBuf)) - { - /* That's bad. Force reading the page again. */ - XLogReaderInvalReadState(state); + /* + * Data is not in our buffer. + * + * Every time we actually read the segment, even if we looked at parts of + * it before, we need to do verification as the page_read callback might + * now be rereading data from a different source. + * + * Whenever switching to a new WAL segment, we read the first page of the + * file and validate its header, even if that's not where the target + * record is. This is so that we can check the additional identification + * info that is present in the first page's "long" header. + */ + if (targetSegNo != state->seg.ws_segno && targetPageOff != 0) + { + XLogRecPtr targetSegmentPtr = pageptr - targetPageOff; - return false; - } + readLen = state->routine.page_read(state, targetSegmentPtr, XLOG_BLCKSZ, + state->currRecPtr, + state->readBuf); + if (readLen < 0) + goto err; - state->page_verified = true; + /* we can be sure to have enough WAL available, we scrolled back */ + Assert(readLen == XLOG_BLCKSZ); - XLByteToSeg(state->readPagePtr, state->seg.ws_segno, - state->segcxt.ws_segsize); + if (!XLogReaderValidatePageHeader(state, targetSegmentPtr, + state->readBuf)) + goto err; } /* - * The loaded page may not be the one caller is supposing to read when we - * are verifying the first page of new segment. In that case, skip further - * verification and immediately load the target page. + * First, read the requested data length, but at least a short page header + * so that we can validate it. */ - if (state->page_verified && pageptr == state->readPagePtr) - { - /* - * calculate additional length for page header keeping the total - * length within the block size. - */ - if (!header_inclusive) - { - uint32 pageHeaderSize = - XLogPageHeaderSize((XLogPageHeader) state->readBuf); + readLen = state->routine.page_read(state, pageptr, Max(reqLen, SizeOfXLogShortPHD), + state->currRecPtr, + state->readBuf); + if (readLen < 0) + goto err; - addLen = pageHeaderSize; - if (reqLen + pageHeaderSize <= XLOG_BLCKSZ) - addLen = pageHeaderSize; - else - addLen = XLOG_BLCKSZ - reqLen; - } + Assert(readLen <= XLOG_BLCKSZ); - /* Return if we already have it. */ - if (reqLen + addLen <= state->readLen) - return false; - } + /* Do we have enough data to check the header length? */ + if (readLen <= SizeOfXLogShortPHD) + goto err; - /* Data is not in our buffer, request the caller for it. */ - XLByteToSeg(pageptr, targetSegNo, state->segcxt.ws_segsize); - targetPageOff = XLogSegmentOffset(pageptr, state->segcxt.ws_segsize); - Assert((pageptr % XLOG_BLCKSZ) == 0); + Assert(readLen >= reqLen); - /* - * Every time we request to load new data of a page to the caller, even if - * we looked at a part of it before, we need to do verification on the - * next invocation as the caller might now be rereading data from a - * different source. - */ - state->page_verified = false; + hdr = (XLogPageHeader) state->readBuf; - /* - * Whenever switching to a new WAL segment, we read the first page of the - * file and validate its header, even if that's not where the target - * record is. This is so that we can check the additional identification - * info that is present in the first page's "long" header. Don't do this - * if the caller requested the first page in the segment. - */ - if (targetSegNo != state->seg.ws_segno && targetPageOff != 0) + /* still not enough */ + if (readLen < XLogPageHeaderSize(hdr)) { - /* - * Then we'll see that the targetSegNo now matches the ws_segno, and - * will not come back here, but will request the actual target page. - */ - state->readPagePtr = pageptr - targetPageOff; - state->reqLen = XLOG_BLCKSZ; - return true; + readLen = state->routine.page_read(state, pageptr, XLogPageHeaderSize(hdr), + state->currRecPtr, + state->readBuf); + if (readLen < 0) + goto err; } /* - * Request the caller to load the page. We need at least a short page - * header so that we can validate it. + * Now that we know we have the full header, validate it. */ - state->readPagePtr = pageptr; - state->reqLen = Max(reqLen + addLen, SizeOfXLogShortPHD); - return true; + if (!XLogReaderValidatePageHeader(state, pageptr, (char *) hdr)) + goto err; + + /* update read state information */ + state->seg.ws_segno = targetSegNo; + state->segoff = targetPageOff; + state->readLen = readLen; + + return readLen; + +err: + XLogReaderInvalReadState(state); + return -1; } /* @@ -1256,7 +673,9 @@ XLogNeedData(XLogReaderState *state, XLogRecPtr pageptr, int reqLen, static void XLogReaderInvalReadState(XLogReaderState *state) { - state->readPagePtr = InvalidXLogRecPtr; + state->seg.ws_segno = 0; + state->segoff = 0; + state->readLen = 0; } /* @@ -1264,12 +683,11 @@ XLogReaderInvalReadState(XLogReaderState *state) * * This is just a convenience subroutine to avoid duplicated code in * XLogReadRecord. It's not intended for use from anywhere else. - * - * If PrevRecPtr is valid, the xl_prev is is cross-checked with it. */ static bool ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr, - XLogRecPtr PrevRecPtr, XLogRecord *record) + XLogRecPtr PrevRecPtr, XLogRecord *record, + bool randAccess) { if (record->xl_tot_len < SizeOfXLogRecord) { @@ -1286,7 +704,7 @@ ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr, record->xl_rmid, LSN_FORMAT_ARGS(RecPtr)); return false; } - if (PrevRecPtr == InvalidXLogRecPtr) + if (randAccess) { /* * We can't exactly verify the prev-link, but surely it should be less @@ -1504,22 +922,6 @@ XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr, * here. */ -XLogFindNextRecordState * -InitXLogFindNextRecord(XLogReaderState *reader_state, XLogRecPtr start_ptr) -{ - XLogFindNextRecordState *state = (XLogFindNextRecordState *) - palloc_extended(sizeof(XLogFindNextRecordState), - MCXT_ALLOC_NO_OOM | MCXT_ALLOC_ZERO); - if (!state) - return NULL; - - state->reader_state = reader_state; - state->targetRecPtr = start_ptr; - state->currRecPtr = start_ptr; - - return state; -} - /* * Find the first record with an lsn >= RecPtr. * @@ -1531,25 +933,27 @@ InitXLogFindNextRecord(XLogReaderState *reader_state, XLogRecPtr start_ptr) * This positions the reader, like XLogBeginRead(), so that the next call to * XLogReadRecord() will read the next valid record. */ -bool -XLogFindNextRecord(XLogFindNextRecordState *state) +XLogRecPtr +XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr) { + XLogRecPtr tmpRecPtr; + XLogRecPtr found = InvalidXLogRecPtr; XLogPageHeader header; - XLogRecord *record; - XLogReadRecordResult result; char *errormsg; - Assert(!XLogRecPtrIsInvalid(state->currRecPtr)); + Assert(!XLogRecPtrIsInvalid(RecPtr)); /* * skip over potential continuation data, keeping in mind that it may span * multiple pages */ + tmpRecPtr = RecPtr; while (true) { XLogRecPtr targetPagePtr; int targetRecOff; uint32 pageHeaderSize; + int readLen; /* * Compute targetRecOff. It should typically be equal or greater than @@ -1557,27 +961,27 @@ XLogFindNextRecord(XLogFindNextRecordState *state) * that, except when caller has explicitly specified the offset that * falls somewhere there or when we are skipping multi-page * continuation record. It doesn't matter though because - * XLogNeedData() is prepared to handle that and will read at least - * short page-header worth of data + * ReadPageInternal() is prepared to handle that and will read at + * least short page-header worth of data */ - targetRecOff = state->currRecPtr % XLOG_BLCKSZ; + targetRecOff = tmpRecPtr % XLOG_BLCKSZ; /* scroll back to page boundary */ - targetPagePtr = state->currRecPtr - targetRecOff; + targetPagePtr = tmpRecPtr - targetRecOff; - if (XLogNeedData(state->reader_state, targetPagePtr, targetRecOff, - targetRecOff != 0)) - return true; - - if (!state->reader_state->page_verified) + /* Read the page containing the record */ + readLen = ReadPageInternal(state, targetPagePtr, targetRecOff); + if (readLen < 0) goto err; - header = (XLogPageHeader) state->reader_state->readBuf; + header = (XLogPageHeader) state->readBuf; pageHeaderSize = XLogPageHeaderSize(header); - /* we should have read the page header */ - Assert(state->reader_state->readLen >= pageHeaderSize); + /* make sure we have enough data for the page header */ + readLen = ReadPageInternal(state, targetPagePtr, pageHeaderSize); + if (readLen < 0) + goto err; /* skip over potential continuation data */ if (header->xlp_info & XLP_FIRST_IS_CONTRECORD) @@ -1592,21 +996,21 @@ XLogFindNextRecord(XLogFindNextRecordState *state) * Note that record headers are MAXALIGN'ed */ if (MAXALIGN(header->xlp_rem_len) >= (XLOG_BLCKSZ - pageHeaderSize)) - state->currRecPtr = targetPagePtr + XLOG_BLCKSZ; + tmpRecPtr = targetPagePtr + XLOG_BLCKSZ; else { /* * The previous continuation record ends in this page. Set - * state->currRecPtr to point to the first valid record + * tmpRecPtr to point to the first valid record */ - state->currRecPtr = targetPagePtr + pageHeaderSize + tmpRecPtr = targetPagePtr + pageHeaderSize + MAXALIGN(header->xlp_rem_len); break; } } else { - state->currRecPtr = targetPagePtr + pageHeaderSize; + tmpRecPtr = targetPagePtr + pageHeaderSize; break; } } @@ -1616,36 +1020,31 @@ XLogFindNextRecord(XLogFindNextRecordState *state) * because either we're at the first record after the beginning of a page * or we just jumped over the remaining data of a continuation. */ - XLogBeginRead(state->reader_state, state->currRecPtr); - while ((result = XLogReadRecord(state->reader_state, &record, &errormsg)) != - XLREAD_FAIL) + XLogBeginRead(state, tmpRecPtr); + while (XLogReadRecord(state, &errormsg) != NULL) { - if (result == XLREAD_NEED_DATA) - return true; - /* past the record we've found, break out */ - if (state->targetRecPtr <= state->reader_state->ReadRecPtr) + if (RecPtr <= state->ReadRecPtr) { /* Rewind the reader to the beginning of the last record. */ - state->currRecPtr = state->reader_state->ReadRecPtr; - XLogBeginRead(state->reader_state, state->currRecPtr); - return false; + found = state->ReadRecPtr; + XLogBeginRead(state, found); + return found; } } err: - XLogReaderInvalReadState(state->reader_state); + XLogReaderInvalReadState(state); - state->currRecPtr = InvalidXLogRecPtr;; - return false; + return InvalidXLogRecPtr; } #endif /* FRONTEND */ /* - * Helper function to ease writing of routines that read raw WAL data. - * If this function is used, caller must supply a segment_open callback and - * segment_close callback as that is used here. + * Helper function to ease writing of XLogRoutine->page_read callbacks. + * If this function is used, caller must supply a segment_open callback in + * 'state', as that is used here. * * Read 'count' bytes into 'buf', starting at location 'startptr', from WAL * fetched from timeline 'tli'. @@ -1658,7 +1057,6 @@ err: */ bool WALRead(XLogReaderState *state, - WALSegmentOpenCB segopenfn, WALSegmentCloseCB segclosefn, char *buf, XLogRecPtr startptr, Size count, TimeLineID tli, WALReadError *errinfo) { @@ -1690,10 +1088,10 @@ WALRead(XLogReaderState *state, XLogSegNo nextSegNo; if (state->seg.ws_file >= 0) - segclosefn(state); + state->routine.segment_close(state); XLByteToSeg(recptr, nextSegNo, state->segcxt.ws_segsize); - segopenfn(state, nextSegNo, &tli); + state->routine.segment_open(state, nextSegNo, &tli); /* This shouldn't happen -- indicates a bug in segment_open */ Assert(state->seg.ws_file >= 0); @@ -1745,84 +1143,34 @@ WALRead(XLogReaderState *state, * ---------------------------------------- */ -/* - * Private function to reset the state, forgetting all decoded records, if we - * are asked to move to a new read position. - */ +/* private function to reset the state between records */ static void ResetDecoder(XLogReaderState *state) { - DecodedXLogRecord *r; + int block_id; - /* Reset the decoded record queue, freeing any oversized records. */ - while ((r = state->decode_queue_tail)) - { - state->decode_queue_tail = r->next; - if (r->oversized) - pfree(r); - } - state->decode_queue_head = NULL; - state->decode_queue_tail = NULL; - state->record = NULL; - state->decoding = NULL; - - /* Reset the decode buffer to empty. */ - state->decode_buffer_head = state->decode_buffer; - state->decode_buffer_tail = state->decode_buffer; + state->decoded_record = NULL; - /* Clear error state. */ - state->errormsg_buf[0] = '\0'; - state->errormsg_deferred = false; -} + state->main_data_len = 0; -/* - * Compute the maximum possible amount of padding that could be required to - * decode a record, given xl_tot_len from the record's header. This is the - * amount of output buffer space that we need to decode a record, though we - * might not finish up using it all. - * - * This computation is pessimistic and assumes the maximum possible number of - * blocks, due to lack of better information. - */ -size_t -DecodeXLogRecordRequiredSpace(size_t xl_tot_len) -{ - size_t size = 0; - - /* Account for the fixed size part of the decoded record struct. */ - size += offsetof(DecodedXLogRecord, blocks[0]); - /* Account for the flexible blocks array of maximum possible size. */ - size += sizeof(DecodedBkpBlock) * (XLR_MAX_BLOCK_ID + 1); - /* Account for all the raw main and block data. */ - size += xl_tot_len; - /* We might insert padding before main_data. */ - size += (MAXIMUM_ALIGNOF - 1); - /* We might insert padding before each block's data. */ - size += (MAXIMUM_ALIGNOF - 1) * (XLR_MAX_BLOCK_ID + 1); - /* We might insert padding at the end. */ - size += (MAXIMUM_ALIGNOF - 1); - - return size; + for (block_id = 0; block_id <= state->max_block_id; block_id++) + { + state->blocks[block_id].in_use = false; + state->blocks[block_id].has_image = false; + state->blocks[block_id].has_data = false; + state->blocks[block_id].apply_image = false; + } + state->max_block_id = -1; } /* - * Decode a record. "decoded" must point to a MAXALIGNed memory area that has - * space for at least DecodeXLogRecordRequiredSpace(record) bytes. On - * success, decoded->size contains the actual space occupied by the decoded - * record, which may turn out to be less. - * - * Only decoded->oversized member must be initialized already, and will not be - * modified. Other members will be initialized as required. + * Decode the previously read record. * * On error, a human-readable error message is returned in *errormsg, and * the return value is false. */ bool -DecodeXLogRecord(XLogReaderState *state, - DecodedXLogRecord *decoded, - XLogRecord *record, - XLogRecPtr lsn, - char **errormsg) +DecodeXLogRecord(XLogReaderState *state, XLogRecord *record, char **errormsg) { /* * read next _size bytes from record buffer, but check for overrun first. @@ -1837,20 +1185,17 @@ DecodeXLogRecord(XLogReaderState *state, } while(0) char *ptr; - char *out; uint32 remaining; uint32 datatotal; RelFileNode *rnode = NULL; uint8 block_id; - decoded->header = *record; - decoded->lsn = lsn; - decoded->next = NULL; - decoded->record_origin = InvalidRepOriginId; - decoded->toplevel_xid = InvalidTransactionId; - decoded->main_data = NULL; - decoded->main_data_len = 0; - decoded->max_block_id = -1; + ResetDecoder(state); + + state->decoded_record = record; + state->record_origin = InvalidRepOriginId; + state->toplevel_xid = InvalidTransactionId; + ptr = (char *) record; ptr += SizeOfXLogRecord; remaining = record->xl_tot_len - SizeOfXLogRecord; @@ -1868,7 +1213,7 @@ DecodeXLogRecord(XLogReaderState *state, COPY_HEADER_FIELD(&main_data_len, sizeof(uint8)); - decoded->main_data_len = main_data_len; + state->main_data_len = main_data_len; datatotal += main_data_len; break; /* by convention, the main data fragment is * always last */ @@ -1879,18 +1224,18 @@ DecodeXLogRecord(XLogReaderState *state, uint32 main_data_len; COPY_HEADER_FIELD(&main_data_len, sizeof(uint32)); - decoded->main_data_len = main_data_len; + state->main_data_len = main_data_len; datatotal += main_data_len; break; /* by convention, the main data fragment is * always last */ } else if (block_id == XLR_BLOCK_ID_ORIGIN) { - COPY_HEADER_FIELD(&decoded->record_origin, sizeof(RepOriginId)); + COPY_HEADER_FIELD(&state->record_origin, sizeof(RepOriginId)); } else if (block_id == XLR_BLOCK_ID_TOPLEVEL_XID) { - COPY_HEADER_FIELD(&decoded->toplevel_xid, sizeof(TransactionId)); + COPY_HEADER_FIELD(&state->toplevel_xid, sizeof(TransactionId)); } else if (block_id <= XLR_MAX_BLOCK_ID) { @@ -1898,11 +1243,7 @@ DecodeXLogRecord(XLogReaderState *state, DecodedBkpBlock *blk; uint8 fork_flags; - /* mark any intervening block IDs as not in use */ - for (int i = decoded->max_block_id + 1; i < block_id; ++i) - decoded->blocks[i].in_use = false; - - if (block_id <= decoded->max_block_id) + if (block_id <= state->max_block_id) { report_invalid_record(state, "out-of-order block_id %u at %X/%X", @@ -1910,9 +1251,9 @@ DecodeXLogRecord(XLogReaderState *state, LSN_FORMAT_ARGS(state->ReadRecPtr)); goto err; } - decoded->max_block_id = block_id; + state->max_block_id = block_id; - blk = &decoded->blocks[block_id]; + blk = &state->blocks[block_id]; blk->in_use = true; blk->apply_image = false; @@ -1922,8 +1263,6 @@ DecodeXLogRecord(XLogReaderState *state, blk->has_image = ((fork_flags & BKPBLOCK_HAS_IMAGE) != 0); blk->has_data = ((fork_flags & BKPBLOCK_HAS_DATA) != 0); - blk->recent_buffer = InvalidBuffer; - COPY_HEADER_FIELD(&blk->data_len, sizeof(uint16)); /* cross-check that the HAS_DATA flag is set iff data_length > 0 */ if (blk->has_data && blk->data_len == 0) @@ -2058,18 +1397,17 @@ DecodeXLogRecord(XLogReaderState *state, /* * Ok, we've parsed the fragment headers, and verified that the total * length of the payload in the fragments is equal to the amount of data - * left. Copy the data of each fragment to contiguous space after the - * blocks array, inserting alignment padding before the data fragments so - * they can be cast to struct pointers by REDO routines. + * left. Copy the data of each fragment to a separate buffer. + * + * We could just set up pointers into readRecordBuf, but we want to align + * the data for the convenience of the callers. Backup images are not + * copied, however; they don't need alignment. */ - out = ((char *) decoded) + - offsetof(DecodedXLogRecord, blocks) + - sizeof(decoded->blocks[0]) * (decoded->max_block_id + 1); /* block data first */ - for (block_id = 0; block_id <= decoded->max_block_id; block_id++) + for (block_id = 0; block_id <= state->max_block_id; block_id++) { - DecodedBkpBlock *blk = &decoded->blocks[block_id]; + DecodedBkpBlock *blk = &state->blocks[block_id]; if (!blk->in_use) continue; @@ -2078,36 +1416,57 @@ DecodeXLogRecord(XLogReaderState *state, if (blk->has_image) { - /* no need to align image */ - blk->bkp_image = out; - memcpy(out, ptr, blk->bimg_len); + blk->bkp_image = ptr; ptr += blk->bimg_len; - out += blk->bimg_len; } if (blk->has_data) { - out = (char *) MAXALIGN(out); - blk->data = out; + if (!blk->data || blk->data_len > blk->data_bufsz) + { + if (blk->data) + pfree(blk->data); + + /* + * Force the initial request to be BLCKSZ so that we don't + * waste time with lots of trips through this stanza as a + * result of WAL compression. + */ + blk->data_bufsz = MAXALIGN(Max(blk->data_len, BLCKSZ)); + blk->data = palloc(blk->data_bufsz); + } memcpy(blk->data, ptr, blk->data_len); ptr += blk->data_len; - out += blk->data_len; } } /* and finally, the main data */ - if (decoded->main_data_len > 0) + if (state->main_data_len > 0) { - out = (char *) MAXALIGN(out); - decoded->main_data = out; - memcpy(decoded->main_data, ptr, decoded->main_data_len); - ptr += decoded->main_data_len; - out += decoded->main_data_len; - } + if (!state->main_data || state->main_data_len > state->main_data_bufsz) + { + if (state->main_data) + pfree(state->main_data); - /* Report the actual size we used. */ - decoded->size = MAXALIGN(out - (char *) decoded); - Assert(DecodeXLogRecordRequiredSpace(record->xl_tot_len) >= - decoded->size); + /* + * main_data_bufsz must be MAXALIGN'ed. In many xlog record + * types, we omit trailing struct padding on-disk to save a few + * bytes; but compilers may generate accesses to the xlog struct + * that assume that padding bytes are present. If the palloc + * request is not large enough to include such padding bytes then + * we'll get valgrind complaints due to otherwise-harmless fetches + * of the padding bytes. + * + * In addition, force the initial request to be reasonably large + * so that we don't waste time with lots of trips through this + * stanza. BLCKSZ / 2 seems like a good compromise choice. + */ + state->main_data_bufsz = MAXALIGN(Max(state->main_data_len, + BLCKSZ / 2)); + state->main_data = palloc(state->main_data_bufsz); + } + memcpy(state->main_data, ptr, state->main_data_len); + ptr += state->main_data_len; + } return true; @@ -2132,30 +1491,18 @@ bool XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id, RelFileNode *rnode, ForkNumber *forknum, BlockNumber *blknum) { - return XLogRecGetRecentBuffer(record, block_id, rnode, forknum, blknum, - NULL); -} - -bool -XLogRecGetRecentBuffer(XLogReaderState *record, uint8 block_id, - RelFileNode *rnode, ForkNumber *forknum, - BlockNumber *blknum, Buffer *recent_buffer) -{ DecodedBkpBlock *bkpb; - if (block_id > record->record->max_block_id || - !record->record->blocks[block_id].in_use) + if (!record->blocks[block_id].in_use) return false; - bkpb = &record->record->blocks[block_id]; + bkpb = &record->blocks[block_id]; if (rnode) *rnode = bkpb->rnode; if (forknum) *forknum = bkpb->forknum; if (blknum) *blknum = bkpb->blkno; - if (recent_buffer) - *recent_buffer = bkpb->recent_buffer; return true; } @@ -2169,11 +1516,10 @@ XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len) { DecodedBkpBlock *bkpb; - if (block_id > record->record->max_block_id || - !record->record->blocks[block_id].in_use) + if (!record->blocks[block_id].in_use) return NULL; - bkpb = &record->record->blocks[block_id]; + bkpb = &record->blocks[block_id]; if (!bkpb->has_data) { @@ -2201,13 +1547,12 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page) char *ptr; PGAlignedBlock tmp; - if (block_id > record->record->max_block_id || - !record->record->blocks[block_id].in_use) + if (!record->blocks[block_id].in_use) return false; - if (!record->record->blocks[block_id].has_image) + if (!record->blocks[block_id].has_image) return false; - bkpb = &record->record->blocks[block_id]; + bkpb = &record->blocks[block_id]; ptr = bkpb->bkp_image; if (bkpb->bimg_info & BKPIMAGE_IS_COMPRESSED) |