135 lines
4.0 KiB
C
135 lines
4.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* walmethods.h
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/bin/pg_basebackup/walmethods.h
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*-------------------------------------------------------------------------
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*/
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#include "common/compression.h"
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struct WalWriteMethod;
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typedef struct WalWriteMethod WalWriteMethod;
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typedef struct
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{
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WalWriteMethod *wwmethod;
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off_t currpos;
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char *pathname;
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/*
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* MORE DATA FOLLOWS AT END OF STRUCT
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*
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* Each WalWriteMethod is expected to embed this as the first member of a
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* larger struct with method-specific fields following.
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*/
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} Walfile;
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typedef enum
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{
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CLOSE_NORMAL,
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CLOSE_UNLINK,
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CLOSE_NO_RENAME
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} WalCloseMethod;
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/*
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* Table of callbacks for a WalWriteMethod.
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*/
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typedef struct WalWriteMethodOps
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{
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/*
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* Open a target file. Returns Walfile, or NULL if open failed. If a temp
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* suffix is specified, a file with that name will be opened, and then
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* automatically renamed in close(). If pad_to_size is specified, the file
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* will be padded with NUL up to that size, if supported by the Walmethod.
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*/
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Walfile *(*open_for_write) (WalWriteMethod *wwmethod, const char *pathname, const char *temp_suffix, size_t pad_to_size);
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/*
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* Close an open Walfile, using one or more methods for handling automatic
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* unlinking etc. Returns 0 on success, other values for error.
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*/
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int (*close) (Walfile *f, WalCloseMethod method);
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/* Check if a file exist */
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bool (*existsfile) (WalWriteMethod *wwmethod, const char *pathname);
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/* Return the size of a file, or -1 on failure. */
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ssize_t (*get_file_size) (WalWriteMethod *wwmethod, const char *pathname);
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/*
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* Return the name of the current file to work on in pg_malloc()'d string,
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* without the base directory. This is useful for logging.
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*/
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char *(*get_file_name) (WalWriteMethod *wwmethod, const char *pathname, const char *temp_suffix);
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/*
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* Write count number of bytes to the file, and return the number of bytes
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* actually written or -1 for error.
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*/
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ssize_t (*write) (Walfile *f, const void *buf, size_t count);
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/*
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* fsync the contents of the specified file. Returns 0 on success.
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*/
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int (*sync) (Walfile *f);
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/*
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* Clean up the Walmethod, closing any shared resources. For methods like
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* tar, this includes writing updated headers. Returns true if the
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* close/write/sync of shared resources succeeded, otherwise returns false
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* (but the resources are still closed).
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*/
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bool (*finish) (WalWriteMethod *wwmethod);
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/*
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* Free subsidiary data associated with the WalWriteMethod, and the
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* WalWriteMethod itself.
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*/
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void (*free) (WalWriteMethod *wwmethod);
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} WalWriteMethodOps;
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/*
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* A WalWriteMethod structure represents a way of writing streaming WAL as
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* it's received.
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*
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* All methods that have a failure return indicator will set lasterrstring
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* or lasterrno (the former takes precedence) so that the caller can signal
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* a suitable error.
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*/
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struct WalWriteMethod
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{
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const WalWriteMethodOps *ops;
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pg_compress_algorithm compression_algorithm;
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int compression_level;
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bool sync;
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const char *lasterrstring; /* if set, takes precedence over lasterrno */
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int lasterrno;
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/*
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* MORE DATA FOLLOWS AT END OF STRUCT
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*
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* Each WalWriteMethod is expected to embed this as the first member of a
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* larger struct with method-specific fields following.
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*/
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};
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/*
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* Available WAL methods:
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* - WalDirectoryMethod - write WAL to regular files in a standard pg_wal
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* - WalTarMethod - write WAL to a tarfile corresponding to pg_wal
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* (only implements the methods required for pg_basebackup,
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* not all those required for pg_receivewal)
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*/
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WalWriteMethod *CreateWalDirectoryMethod(const char *basedir,
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pg_compress_algorithm compression_algorithm,
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int compression_level, bool sync);
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WalWriteMethod *CreateWalTarMethod(const char *tarbase,
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pg_compress_algorithm compression_algorithm,
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int compression_level, bool sync);
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const char *GetLastWalMethodError(WalWriteMethod *wwmethod);
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