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authorgalaxycrab <UgnineSirdis@ydb.tech>2023-11-23 11:26:33 +0300
committergalaxycrab <UgnineSirdis@ydb.tech>2023-11-23 12:01:57 +0300
commit44354d0fc55926c1d4510d1d2c9c9f6a1a5e9300 (patch)
treecb4d75cd1c6dbc3da0ed927337fd8d1b6ed9da84 /contrib/libs/libpq/src/include/access/xlogreader.h
parent0e69bf615395fdd48ecee032faaec81bc468b0b8 (diff)
downloadydb-44354d0fc55926c1d4510d1d2c9c9f6a1a5e9300.tar.gz
YQ Connector:test INNER JOIN
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+/*-------------------------------------------------------------------------
+ *
+ * xlogreader.h
+ * Definitions for the generic XLog reading facility
+ *
+ * Portions Copyright (c) 2013-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/include/access/xlogreader.h
+ *
+ * NOTES
+ * See the definition of the XLogReaderState struct for instructions on
+ * how to use the XLogReader infrastructure.
+ *
+ * The basic idea is to allocate an XLogReaderState via
+ * XLogReaderAllocate(), position the reader to the first record with
+ * XLogBeginRead() or XLogFindNextRecord(), and call XLogReadRecord()
+ * until it returns NULL.
+ *
+ * Callers supply a page_read callback if they want to call
+ * XLogReadRecord or XLogFindNextRecord; it can be passed in as NULL
+ * otherwise. The WALRead function can be used as a helper to write
+ * page_read callbacks, but it is not mandatory; callers that use it,
+ * must supply segment_open callbacks. The segment_close callback
+ * must always be supplied.
+ *
+ * After reading a record with XLogReadRecord(), it's decomposed into
+ * the per-block and main data parts, and the parts can be accessed
+ * with the XLogRec* macros and functions. You can also decode a
+ * record that's already constructed in memory, without reading from
+ * disk, by calling the DecodeXLogRecord() function.
+ *-------------------------------------------------------------------------
+ */
+#ifndef XLOGREADER_H
+#define XLOGREADER_H
+
+#ifndef FRONTEND
+#include "access/transam.h"
+#endif
+
+#include "access/xlogrecord.h"
+#include "storage/buf.h"
+
+/* WALOpenSegment represents a WAL segment being read. */
+typedef struct WALOpenSegment
+{
+ int ws_file; /* segment file descriptor */
+ XLogSegNo ws_segno; /* segment number */
+ TimeLineID ws_tli; /* timeline ID of the currently open file */
+} WALOpenSegment;
+
+/* WALSegmentContext carries context information about WAL segments to read */
+typedef struct WALSegmentContext
+{
+ char ws_dir[MAXPGPATH];
+ int ws_segsize;
+} WALSegmentContext;
+
+typedef struct XLogReaderState XLogReaderState;
+
+/* Function type definitions for various xlogreader interactions */
+typedef int (*XLogPageReadCB) (XLogReaderState *xlogreader,
+ XLogRecPtr targetPagePtr,
+ int reqLen,
+ XLogRecPtr targetRecPtr,
+ char *readBuf);
+typedef void (*WALSegmentOpenCB) (XLogReaderState *xlogreader,
+ XLogSegNo nextSegNo,
+ TimeLineID *tli_p);
+typedef void (*WALSegmentCloseCB) (XLogReaderState *xlogreader);
+
+typedef struct XLogReaderRoutine
+{
+ /*
+ * Data input callback
+ *
+ * This callback shall read at least reqLen valid bytes of the xlog page
+ * starting at targetPagePtr, and store them in readBuf. The callback
+ * shall return the number of bytes read (never more than XLOG_BLCKSZ), or
+ * -1 on failure. The callback shall sleep, if necessary, to wait for the
+ * requested bytes to become available. The callback will not be invoked
+ * again for the same page unless more than the returned number of bytes
+ * are needed.
+ *
+ * targetRecPtr is the position of the WAL record we're reading. Usually
+ * it is equal to targetPagePtr + reqLen, but sometimes xlogreader needs
+ * to read and verify the page or segment header, before it reads the
+ * actual WAL record it's interested in. In that case, targetRecPtr can
+ * be used to determine which timeline to read the page from.
+ *
+ * The callback shall set ->seg.ws_tli to the TLI of the file the page was
+ * read from.
+ */
+ XLogPageReadCB page_read;
+
+ /*
+ * Callback to open the specified WAL segment for reading. ->seg.ws_file
+ * shall be set to the file descriptor of the opened segment. In case of
+ * failure, an error shall be raised by the callback and it shall not
+ * return.
+ *
+ * "nextSegNo" is the number of the segment to be opened.
+ *
+ * "tli_p" is an input/output argument. WALRead() uses it to pass the
+ * timeline in which the new segment should be found, but the callback can
+ * use it to return the TLI that it actually opened.
+ */
+ WALSegmentOpenCB segment_open;
+
+ /*
+ * WAL segment close callback. ->seg.ws_file shall be set to a negative
+ * number.
+ */
+ WALSegmentCloseCB segment_close;
+} XLogReaderRoutine;
+
+#define XL_ROUTINE(...) &(XLogReaderRoutine){__VA_ARGS__}
+
+typedef struct
+{
+ /* Is this block ref in use? */
+ bool in_use;
+
+ /* Identify the block this refers to */
+ RelFileLocator rlocator;
+ ForkNumber forknum;
+ BlockNumber blkno;
+
+ /* Prefetching workspace. */
+ Buffer prefetch_buffer;
+
+ /* copy of the fork_flags field from the XLogRecordBlockHeader */
+ uint8 flags;
+
+ /* Information on full-page image, if any */
+ bool has_image; /* has image, even for consistency checking */
+ bool apply_image; /* has image that should be restored */
+ char *bkp_image;
+ uint16 hole_offset;
+ uint16 hole_length;
+ uint16 bimg_len;
+ uint8 bimg_info;
+
+ /* Buffer holding the rmgr-specific data associated with this block */
+ bool has_data;
+ char *data;
+ uint16 data_len;
+ uint16 data_bufsz;
+} DecodedBkpBlock;
+
+/*
+ * The decoded contents of a record. This occupies a contiguous region of
+ * memory, with main_data and blocks[n].data pointing to memory after the
+ * members declared here.
+ */
+typedef struct DecodedXLogRecord
+{
+ /* Private member used for resource management. */
+ size_t size; /* total size of decoded record */
+ bool oversized; /* outside the regular decode buffer? */
+ struct DecodedXLogRecord *next; /* decoded record queue link */
+
+ /* Public members. */
+ XLogRecPtr lsn; /* location */
+ XLogRecPtr next_lsn; /* location of next record */
+ XLogRecord header; /* header */
+ RepOriginId record_origin;
+ TransactionId toplevel_xid; /* XID of top-level transaction */
+ char *main_data; /* record's main data portion */
+ uint32 main_data_len; /* main data portion's length */
+ int max_block_id; /* highest block_id in use (-1 if none) */
+ DecodedBkpBlock blocks[FLEXIBLE_ARRAY_MEMBER];
+} DecodedXLogRecord;
+
+struct XLogReaderState
+{
+ /*
+ * Operational callbacks
+ */
+ XLogReaderRoutine routine;
+
+ /* ----------------------------------------
+ * Public parameters
+ * ----------------------------------------
+ */
+
+ /*
+ * System identifier of the xlog files we're about to read. Set to zero
+ * (the default value) if unknown or unimportant.
+ */
+ uint64 system_identifier;
+
+ /*
+ * Opaque data for callbacks to use. Not used by XLogReader.
+ */
+ void *private_data;
+
+ /*
+ * Start and end point of last record read. EndRecPtr is also used as the
+ * position to read next. Calling XLogBeginRead() sets EndRecPtr to the
+ * starting position and ReadRecPtr to invalid.
+ *
+ * Start and end point of last record returned by XLogReadRecord(). These
+ * are also available as record->lsn and record->next_lsn.
+ */
+ XLogRecPtr ReadRecPtr; /* start of last record read */
+ XLogRecPtr EndRecPtr; /* end+1 of last record read */
+
+ /*
+ * Set at the end of recovery: the start point of a partial record at the
+ * end of WAL (InvalidXLogRecPtr if there wasn't one), and the start
+ * location of its first contrecord that went missing.
+ */
+ XLogRecPtr abortedRecPtr;
+ XLogRecPtr missingContrecPtr;
+ /* Set when XLP_FIRST_IS_OVERWRITE_CONTRECORD is found */
+ XLogRecPtr overwrittenRecPtr;
+
+
+ /* ----------------------------------------
+ * Decoded representation of current record
+ *
+ * Use XLogRecGet* functions to investigate the record; these fields
+ * should not be accessed directly.
+ * ----------------------------------------
+ * Start and end point of the last record read and decoded by
+ * XLogReadRecordInternal(). NextRecPtr is also used as the position to
+ * decode next. Calling XLogBeginRead() sets NextRecPtr and EndRecPtr to
+ * the requested starting position.
+ */
+ XLogRecPtr DecodeRecPtr; /* start of last record decoded */
+ XLogRecPtr NextRecPtr; /* end+1 of last record decoded */
+ XLogRecPtr PrevRecPtr; /* start of previous record decoded */
+
+ /* Last record returned by XLogReadRecord(). */
+ DecodedXLogRecord *record;
+
+ /* ----------------------------------------
+ * private/internal state
+ * ----------------------------------------
+ */
+
+ /*
+ * Buffer for decoded records. This is a circular buffer, though
+ * individual records can't be split in the middle, so some space is often
+ * wasted at the end. Oversized records that don't fit in this space are
+ * allocated separately.
+ */
+ char *decode_buffer;
+ size_t decode_buffer_size;
+ bool free_decode_buffer; /* need to free? */
+ char *decode_buffer_head; /* data is read from the head */
+ char *decode_buffer_tail; /* new data is written at the tail */
+
+ /*
+ * Queue of records that have been decoded. This is a linked list that
+ * usually consists of consecutive records in decode_buffer, but may also
+ * contain oversized records allocated with palloc().
+ */
+ DecodedXLogRecord *decode_queue_head; /* oldest decoded record */
+ DecodedXLogRecord *decode_queue_tail; /* newest decoded record */
+
+ /*
+ * Buffer for currently read page (XLOG_BLCKSZ bytes, valid up to at least
+ * readLen bytes)
+ */
+ char *readBuf;
+ uint32 readLen;
+
+ /* last read XLOG position for data currently in readBuf */
+ WALSegmentContext segcxt;
+ WALOpenSegment seg;
+ uint32 segoff;
+
+ /*
+ * beginning of prior page read, and its TLI. Doesn't necessarily
+ * correspond to what's in readBuf; used for timeline sanity checks.
+ */
+ XLogRecPtr latestPagePtr;
+ TimeLineID latestPageTLI;
+
+ /* beginning of the WAL record being read. */
+ XLogRecPtr currRecPtr;
+ /* timeline to read it from, 0 if a lookup is required */
+ TimeLineID currTLI;
+
+ /*
+ * Safe point to read to in currTLI if current TLI is historical
+ * (tliSwitchPoint) or InvalidXLogRecPtr if on current timeline.
+ *
+ * Actually set to the start of the segment containing the timeline switch
+ * that ends currTLI's validity, not the LSN of the switch its self, since
+ * we can't assume the old segment will be present.
+ */
+ XLogRecPtr currTLIValidUntil;
+
+ /*
+ * If currTLI is not the most recent known timeline, the next timeline to
+ * read from when currTLIValidUntil is reached.
+ */
+ TimeLineID nextTLI;
+
+ /*
+ * Buffer for current ReadRecord result (expandable), used when a record
+ * crosses a page boundary.
+ */
+ char *readRecordBuf;
+ uint32 readRecordBufSize;
+
+ /* Buffer to hold error message */
+ char *errormsg_buf;
+ bool errormsg_deferred;
+
+ /*
+ * Flag to indicate to XLogPageReadCB that it should not block waiting for
+ * data.
+ */
+ bool nonblocking;
+};
+
+/*
+ * Check if XLogNextRecord() has any more queued records or an error to return.
+ */
+static inline bool
+XLogReaderHasQueuedRecordOrError(XLogReaderState *state)
+{
+ return (state->decode_queue_head != NULL) || state->errormsg_deferred;
+}
+
+/* Get a new XLogReader */
+extern XLogReaderState *XLogReaderAllocate(int wal_segment_size,
+ const char *waldir,
+ XLogReaderRoutine *routine,
+ void *private_data);
+
+/* Free an XLogReader */
+extern void XLogReaderFree(XLogReaderState *state);
+
+/* Optionally provide a circular decoding buffer to allow readahead. */
+extern void XLogReaderSetDecodeBuffer(XLogReaderState *state,
+ void *buffer,
+ size_t size);
+
+/* Position the XLogReader to given record */
+extern void XLogBeginRead(XLogReaderState *state, XLogRecPtr RecPtr);
+extern XLogRecPtr XLogFindNextRecord(XLogReaderState *state, XLogRecPtr RecPtr);
+
+/* Return values from XLogPageReadCB. */
+typedef enum XLogPageReadResult
+{
+ XLREAD_SUCCESS = 0, /* record is successfully read */
+ XLREAD_FAIL = -1, /* failed during reading a record */
+ XLREAD_WOULDBLOCK = -2 /* nonblocking mode only, no data */
+} XLogPageReadResult;
+
+/* Read the next XLog record. Returns NULL on end-of-WAL or failure */
+extern struct XLogRecord *XLogReadRecord(XLogReaderState *state,
+ char **errormsg);
+
+/* Consume the next record or error. */
+extern DecodedXLogRecord *XLogNextRecord(XLogReaderState *state,
+ char **errormsg);
+
+/* Release the previously returned record, if necessary. */
+extern XLogRecPtr XLogReleasePreviousRecord(XLogReaderState *state);
+
+/* Try to read ahead, if there is data and space. */
+extern DecodedXLogRecord *XLogReadAhead(XLogReaderState *state,
+ bool nonblocking);
+
+/* Validate a page */
+extern bool XLogReaderValidatePageHeader(XLogReaderState *state,
+ XLogRecPtr recptr, char *phdr);
+
+/* Forget error produced by XLogReaderValidatePageHeader(). */
+extern void XLogReaderResetError(XLogReaderState *state);
+
+/*
+ * Error information from WALRead that both backend and frontend caller can
+ * process. Currently only errors from pg_pread can be reported.
+ */
+typedef struct WALReadError
+{
+ int wre_errno; /* errno set by the last pg_pread() */
+ int wre_off; /* Offset we tried to read from. */
+ int wre_req; /* Bytes requested to be read. */
+ int wre_read; /* Bytes read by the last read(). */
+ WALOpenSegment wre_seg; /* Segment we tried to read from. */
+} WALReadError;
+
+extern bool WALRead(XLogReaderState *state,
+ char *buf, XLogRecPtr startptr, Size count,
+ TimeLineID tli, WALReadError *errinfo);
+
+/* Functions for decoding an XLogRecord */
+
+extern size_t DecodeXLogRecordRequiredSpace(size_t xl_tot_len);
+extern bool DecodeXLogRecord(XLogReaderState *state,
+ DecodedXLogRecord *decoded,
+ XLogRecord *record,
+ XLogRecPtr lsn,
+ char **errormsg);
+
+/*
+ * Macros that provide access to parts of the record most recently returned by
+ * XLogReadRecord() or XLogNextRecord().
+ */
+#define XLogRecGetTotalLen(decoder) ((decoder)->record->header.xl_tot_len)
+#define XLogRecGetPrev(decoder) ((decoder)->record->header.xl_prev)
+#define XLogRecGetInfo(decoder) ((decoder)->record->header.xl_info)
+#define XLogRecGetRmid(decoder) ((decoder)->record->header.xl_rmid)
+#define XLogRecGetXid(decoder) ((decoder)->record->header.xl_xid)
+#define XLogRecGetOrigin(decoder) ((decoder)->record->record_origin)
+#define XLogRecGetTopXid(decoder) ((decoder)->record->toplevel_xid)
+#define XLogRecGetData(decoder) ((decoder)->record->main_data)
+#define XLogRecGetDataLen(decoder) ((decoder)->record->main_data_len)
+#define XLogRecHasAnyBlockRefs(decoder) ((decoder)->record->max_block_id >= 0)
+#define XLogRecMaxBlockId(decoder) ((decoder)->record->max_block_id)
+#define XLogRecGetBlock(decoder, i) (&(decoder)->record->blocks[(i)])
+#define XLogRecHasBlockRef(decoder, block_id) \
+ (((decoder)->record->max_block_id >= (block_id)) && \
+ ((decoder)->record->blocks[block_id].in_use))
+#define XLogRecHasBlockImage(decoder, block_id) \
+ ((decoder)->record->blocks[block_id].has_image)
+#define XLogRecBlockImageApply(decoder, block_id) \
+ ((decoder)->record->blocks[block_id].apply_image)
+#define XLogRecHasBlockData(decoder, block_id) \
+ ((decoder)->record->blocks[block_id].has_data)
+
+#ifndef FRONTEND
+extern FullTransactionId XLogRecGetFullXid(XLogReaderState *record);
+#endif
+
+extern bool RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page);
+extern char *XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len);
+extern void XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
+ RelFileLocator *rlocator, ForkNumber *forknum,
+ BlockNumber *blknum);
+extern bool XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id,
+ RelFileLocator *rlocator, ForkNumber *forknum,
+ BlockNumber *blknum,
+ Buffer *prefetch_buffer);
+
+#endif /* XLOGREADER_H */