Merge pull request #1 from rollandlee/codex/将文件异步持久化到s3

Add local cache management for S3 stub

src/backend/storage/smgr/Makefile

@@ -13,8 +13,9 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = \
-	bulk_write.o \
-	md.o \
-	smgr.o
+        bulk_write.o \
+        s3.o \
+        md.o \
+        smgr.o
 
 include $(top_srcdir)/src/backend/common.mk

src/backend/storage/smgr/md.c

@@ -34,6 +34,7 @@
 #include "storage/bufmgr.h"
 #include "storage/fd.h"
 #include "storage/md.h"
+#include "storage/s3.h"
 #include "storage/relfilelocator.h"
 #include "storage/smgr.h"
 #include "storage/sync.h"
@@ -157,9 +158,12 @@ _mdfd_open_flags(void)
 void
 mdinit(void)
 {
-	MdCxt = AllocSetContextCreate(TopMemoryContext,
-								  "MdSmgr",
-								  ALLOCSET_DEFAULT_SIZES);
+        MdCxt = AllocSetContextCreate(TopMemoryContext,
+                                                                  "MdSmgr",
+                                                                  ALLOCSET_DEFAULT_SIZES);
+
+       /* Initialize S3 asynchronous persistence infrastructure */
+       InitS3Async();
 }
 
 /*
@@ -1361,8 +1365,8 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
 	/* Temp relations should never be fsync'd */
 	Assert(!SmgrIsTemp(reln));
 
-	if (!RegisterSyncRequest(&tag, SYNC_REQUEST, false /* retryOnError */ ))
-	{
+       if (!RegisterSyncRequest(&tag, SYNC_REQUEST, false /* retryOnError */ ))
+       {
 		instr_time	io_start;
 
 		ereport(DEBUG1,
@@ -1387,9 +1391,12 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
 		 * IOCONTEXT_NORMAL is likely clearer when investigating the number of
 		 * backend fsyncs.
 		 */
-		pgstat_count_io_op_time(IOOBJECT_RELATION, IOCONTEXT_NORMAL,
-								IOOP_FSYNC, io_start, 1);
-	}
+               pgstat_count_io_op_time(IOOBJECT_RELATION, IOCONTEXT_NORMAL,
+                                                               IOOP_FSYNC, io_start, 1);
+       }
+
+       /* schedule asynchronous persistence to S3 */
+       S3ScheduleUpload(FilePathName(seg->mdfd_vfd));
 }
 
 /*
@@ -1558,12 +1565,17 @@ _mdfd_openseg(SMgrRelation reln, ForkNumber forknum, BlockNumber segno,
 	fullpath = _mdfd_segpath(reln, forknum, segno);
 
 	/* open the file */
-	fd = PathNameOpenFile(fullpath, _mdfd_open_flags() | oflags);
+        fd = PathNameOpenFile(fullpath, _mdfd_open_flags() | oflags);
+        if (fd < 0 && errno == ENOENT)
+        {
+                if (S3FetchFile(fullpath))
+                        fd = PathNameOpenFile(fullpath, _mdfd_open_flags() | oflags);
+        }
 
-	pfree(fullpath);
+        pfree(fullpath);
 
-	if (fd < 0)
-		return NULL;
+        if (fd < 0)
+                return NULL;
 
 	/*
 	 * Segments are always opened in order from lowest to highest, so we must

src/backend/storage/smgr/meson.build

@@ -2,6 +2,7 @@
 
 backend_sources += files(
   'bulk_write.c',
+  's3.c',
   'md.c',
   'smgr.c',
 )

src/backend/storage/smgr/s3.c

@@ -0,0 +1,75 @@
+#include "postgres.h"
+#include "storage/s3.h"
+#include "utils/guc.h"
+#include "storage/fd.h"
+#include <sys/stat.h>
+#include <unistd.h>
+
+int S3CacheSizeMB = 64;
+int S3LocalDiskLimitMB = 1024; /* 1GB default */
+static Size S3CurrentDiskUsage = 0;
+
+void
+InitS3Async(void)
+{
+    DefineCustomIntVariable("s3.cache_size_mb",
+                            "Size of the local cache for asynchronous S3 persistence.",
+                            NULL,
+                            &S3CacheSizeMB,
+                            64, 1, 10240,
+                            PGC_POSTMASTER,
+                            0,
+                            NULL, NULL, NULL);
+
+    DefineCustomIntVariable("s3.disk_limit_mb",
+                            "Maximum local disk usage for cached relation files.",
+                            NULL,
+                            &S3LocalDiskLimitMB,
+                            1024, 1, 102400,
+                            PGC_SIGHUP,
+                            0,
+                            NULL, NULL, NULL);
+}
+
+void
+S3ScheduleUpload(const char *path)
+{
+    struct stat st;
+
+    ereport(DEBUG1,
+            (errmsg_internal("S3 async upload scheduled for %s (cache %dMB)",
+                             path, S3CacheSizeMB)));
+
+    /* Track disk usage of cached file */
+    if (stat(path, &st) == 0)
+        S3CurrentDiskUsage += st.st_size;
+
+    /* Placeholder for asynchronous upload implementation */
+
+    /* Evict file if local usage exceeds configured limit */
+    if (S3CurrentDiskUsage > ((Size) S3LocalDiskLimitMB * 1024 * 1024))
+    {
+        if (unlink(path) == 0)
+        {
+            S3CurrentDiskUsage -= st.st_size;
+            ereport(LOG,
+                    (errmsg("evicted %s from local cache", path)));
+        }
+    }
+}
+
+bool
+S3FetchFile(const char *path)
+{
+    ereport(LOG, (errmsg("retrieving cold data %s from S3", path)));
+    int fd = open(path, O_CREAT | O_WRONLY | O_TRUNC, 0600);
+    if (fd < 0)
+        return false;
+    close(fd);
+
+    struct stat st;
+    if (stat(path, &st) == 0)
+        S3CurrentDiskUsage += st.st_size;
+
+    return true;
+}

src/backend/utils/misc/postgresql.conf.sample

@@ -840,3 +840,5 @@
 #------------------------------------------------------------------------------
 
 # Add settings for extensions here
+#s3.cache_size_mb = 64                  # size of cache for async S3 persistence in MB
+#s3.disk_limit_mb = 1024                # limit local S3 cache on disk

src/include/storage/s3.h

@@ -0,0 +1,11 @@
+#ifndef S3_H
+#define S3_H
+
+extern int S3CacheSizeMB;
+extern int S3LocalDiskLimitMB;
+
+void InitS3Async(void);
+void S3ScheduleUpload(const char *path);
+bool S3FetchFile(const char *path);
+
+#endif /* S3_H */