1 files changed, 113 insertions, 0 deletions
diff --git a/src/bin/pg_rewind/filemap.h b/src/bin/pg_rewind/filemap.h
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+++ b/src/bin/pg_rewind/filemap.h
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+/*-------------------------------------------------------------------------
+ *
+ * filemap.h
+ *
+ * Copyright (c) 2013-2021, PostgreSQL Global Development Group
+ *-------------------------------------------------------------------------
+ */
+#ifndef FILEMAP_H
+#define FILEMAP_H
+
+#include "datapagemap.h"
+#include "storage/block.h"
+#include "storage/relfilenode.h"
+
+/* these enum values are sorted in the order we want actions to be processed */
+typedef enum
+{
+	FILE_ACTION_UNDECIDED = 0,	/* not decided yet */
+
+	FILE_ACTION_CREATE,			/* create local directory or symbolic link */
+	FILE_ACTION_COPY,			/* copy whole file, overwriting if exists */
+	FILE_ACTION_COPY_TAIL,		/* copy tail from 'source_size' to
+								 * 'target_size' */
+	FILE_ACTION_NONE,			/* no action (we might still copy modified
+								 * blocks based on the parsed WAL) */
+	FILE_ACTION_TRUNCATE,		/* truncate local file to 'newsize' bytes */
+	FILE_ACTION_REMOVE			/* remove local file / directory / symlink */
+} file_action_t;
+
+typedef enum
+{
+	FILE_TYPE_UNDEFINED = 0,
+
+	FILE_TYPE_REGULAR,
+	FILE_TYPE_DIRECTORY,
+	FILE_TYPE_SYMLINK
+} file_type_t;
+
+/*
+ * For every file found in the local or remote system, we have a file entry
+ * that contains information about the file on both systems.  For relation
+ * files, there is also a page map that marks pages in the file that were
+ * changed in the target after the last common checkpoint.
+ *
+ * When gathering information, these are kept in a hash table, private to
+ * filemap.c.  decide_file_actions() fills in the 'action' field, sorts all
+ * the entries, and returns them in an array, ready for executing the actions.
+ */
+typedef struct file_entry_t
+{
+	uint32		status;			/* hash status */
+
+	const char *path;
+	bool		isrelfile;		/* is it a relation data file? */
+
+	/*
+	 * Status of the file in the target.
+	 */
+	bool		target_exists;
+	file_type_t target_type;
+	size_t		target_size;	/* for a regular file */
+	char	   *target_link_target; /* for a symlink */
+
+	/*
+	 * Pages that were modified in the target and need to be replaced from the
+	 * source.
+	 */
+	datapagemap_t target_pages_to_overwrite;
+
+	/*
+	 * Status of the file in the source.
+	 */
+	bool		source_exists;
+	file_type_t source_type;
+	size_t		source_size;
+	char	   *source_link_target; /* for a symlink */
+
+	/*
+	 * What will we do to the file?
+	 */
+	file_action_t action;
+} file_entry_t;
+
+/*
+ * This contains the final decisions on what to do with each file.
+ * 'entries' array contains an entry for each file, sorted in the order
+ * that their actions should executed.
+ */
+typedef struct filemap_t
+{
+	/* Summary information, filled by calculate_totals() */
+	uint64		total_size;		/* total size of the source cluster */
+	uint64		fetch_size;		/* number of bytes that needs to be copied */
+
+	int			nentries;		/* size of 'entries' array */
+	file_entry_t *entries[FLEXIBLE_ARRAY_MEMBER];
+} filemap_t;
+
+/* Functions for populating the filemap */
+extern void filehash_init(void);
+extern void process_source_file(const char *path, file_type_t type,
+								size_t size, const char *link_target);
+extern void process_target_file(const char *path, file_type_t type,
+								size_t size, const char *link_target);
+extern void process_target_wal_block_change(ForkNumber forknum,
+											RelFileNode rnode,
+											BlockNumber blkno);
+
+extern filemap_t *decide_file_actions(void);
+extern void calculate_totals(filemap_t *filemap);
+extern void print_filemap(filemap_t *filemap);
+
+#endif							/* FILEMAP_H */