Extend the BufFile interface.

Allow BufFile to support temporary files that can be used by the single
backend when the corresponding files need to be survived across the
transaction and need to be opened and closed multiple times. Such files
need to be created as a member of a SharedFileSet.

Additionally, this commit implements the interface for BufFileTruncate to
allow files to be truncated up to a particular offset and extends the
BufFileSeek API to support the SEEK_END case. This also adds an option to
provide a mode while opening the shared BufFiles instead of always opening
in read-only mode.

These enhancements in BufFile interface are required for the upcoming
patch to allow the replication apply worker, to handle streamed
in-progress transactions.

Author: Dilip Kumar, Amit Kapila
Reviewed-by: Amit Kapila
Tested-by: Neha Sharma
Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com

4 files changed, 8 insertions, 3 deletions

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 13872013823..807a9c1edf6 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -916,6 +916,7 @@ typedef enum
 	WAIT_EVENT_BASEBACKUP_READ = PG_WAIT_IO,
 	WAIT_EVENT_BUFFILE_READ,
 	WAIT_EVENT_BUFFILE_WRITE,
+	WAIT_EVENT_BUFFILE_TRUNCATE,
 	WAIT_EVENT_CONTROL_FILE_READ,
 	WAIT_EVENT_CONTROL_FILE_SYNC,
 	WAIT_EVENT_CONTROL_FILE_SYNC_UPDATE,
diff --git a/src/include/storage/buffile.h b/src/include/storage/buffile.h
index f4752bab0da..fc34c49522d 100644
--- a/src/include/storage/buffile.h
+++ b/src/include/storage/buffile.h
@@ -48,7 +48,9 @@ extern long BufFileAppend(BufFile *target, BufFile *source);
 
 extern BufFile *BufFileCreateShared(SharedFileSet *fileset, const char *name);
 extern void BufFileExportShared(BufFile *file);
-extern BufFile *BufFileOpenShared(SharedFileSet *fileset, const char *name);
+extern BufFile *BufFileOpenShared(SharedFileSet *fileset, const char *name,
+								  int mode);
 extern void BufFileDeleteShared(SharedFileSet *fileset, const char *name);
+extern void BufFileTruncateShared(BufFile *file, int fileno, off_t offset);
 
 #endif							/* BUFFILE_H */
diff --git a/src/include/storage/fd.h b/src/include/storage/fd.h
index 8cd125d7dfa..e209f047e85 100644
--- a/src/include/storage/fd.h
+++ b/src/include/storage/fd.h
@@ -94,7 +94,7 @@ extern mode_t FileGetRawMode(File file);
 
 /* Operations used for sharing named temporary files */
 extern File PathNameCreateTemporaryFile(const char *name, bool error_on_failure);
-extern File PathNameOpenTemporaryFile(const char *name);
+extern File PathNameOpenTemporaryFile(const char *path, int mode);
 extern bool PathNameDeleteTemporaryFile(const char *name, bool error_on_failure);
 extern void PathNameCreateTemporaryDir(const char *base, const char *name);
 extern void PathNameDeleteTemporaryDir(const char *name);
diff --git a/src/include/storage/sharedfileset.h b/src/include/storage/sharedfileset.h
index 2d6cf077e51..d5edb600af9 100644
--- a/src/include/storage/sharedfileset.h
+++ b/src/include/storage/sharedfileset.h
@@ -37,9 +37,11 @@ typedef struct SharedFileSet
 extern void SharedFileSetInit(SharedFileSet *fileset, dsm_segment *seg);
 extern void SharedFileSetAttach(SharedFileSet *fileset, dsm_segment *seg);
 extern File SharedFileSetCreate(SharedFileSet *fileset, const char *name);
-extern File SharedFileSetOpen(SharedFileSet *fileset, const char *name);
+extern File SharedFileSetOpen(SharedFileSet *fileset, const char *name,
+							  int mode);
 extern bool SharedFileSetDelete(SharedFileSet *fileset, const char *name,
 								bool error_on_failure);
 extern void SharedFileSetDeleteAll(SharedFileSet *fileset);
+extern void SharedFileSetUnregister(SharedFileSet *input_fileset);
 
 #endif