Add the xShmRelease() method to the VFS. The os_unix.c implementation of

the shared memory logic is still non-functional.

FossilOrigin-Name: ed715b47c5f7657fbf901805981867898054b14d

9 files changed, 20 insertions, 68 deletions

diff --git a/src/os_os2.c b/src/os_os2.c
index 04b6dce0e..1c55e4be6 100644
--- a/src/os_os2.c
+++ b/src/os_os2.c
@@ -1111,16 +1111,7 @@ int sqlite3_os_init(void){
     os2Randomness,     /* xRandomness */
     os2Sleep,          /* xSleep */
     os2CurrentTime,    /* xCurrentTime */
-    os2GetLastError    /* xGetLastError */
-    0,                 /* xShmOpen */
-    0,                 /* xShmSize */
-    0,                 /* xShmPush */
-    0,                 /* xShmPull */
-    0,                 /* xShmLock */
-    0,                 /* xShmClose */
-    0,                 /* xShmDelete */
-    0,                 /* xRename */
-    0,                 /* xCurrentTimeInt64 */
+    os2GetLastError,   /* xGetLastError */
   };
   sqlite3_vfs_register(&os2Vfs, 1);
   initUconvObjects();
diff --git a/src/os_unix.c b/src/os_unix.c
index b2cf9be76..d603caa0d 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -4647,8 +4647,13 @@ shm_open_err:
 ** Query and/or changes the size of a shared-memory segment.
 ** The reqSize parameter is the new size of the segment, or -1 to
 ** do just a query.  The size of the segment after resizing is
-** written into pNewSize.  The start of the shared memory buffer
-** is stored in **ppBuffer.
+** written into pNewSize.  A writer lock is held on the shared memory
+** segment while resizing it.
+**
+** If ppBuffer is not NULL, the a reader lock is acquired no the shared
+** memory segment and *ppBuffer is made to point to the start of the 
+** shared memory segment.  xShmRelease() must be called to release the
+** lock.
 */
 static int unixShmSize(
   sqlite3_shm *pSharedMem,  /* Pointer returned by unixShmOpen() */
@@ -4680,6 +4685,14 @@ static int unixShmSize(
 }
 
 /*
+** Release the lock held on the shared memory segment to that other
+** threads are free to resize it if necessary.
+*/
+static int unixShmRelease(sqlite3_shm *pSharedMem){
+  return SQLITE_OK;
+}
+
+/*
 ** Create or release a lock on shared memory.
 */
 static int unixShmLock(
@@ -5934,6 +5947,7 @@ int sqlite3_os_init(void){
     unixGetLastError,     /* xGetLastError */               \
     unixShmOpen,          /* xShmOpen */                    \
     unixShmSize,          /* xShmSize */                    \
+    unixShmRelease,       /* xShmRelease */                 \
     0,                    /* xShmPush */                    \
     0,                    /* xShmPull */                    \
     unixShmLock,          /* xShmLock */                    \
diff --git a/src/os_win.c b/src/os_win.c
index 31c3cffce..cfcf49e36 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -1912,16 +1912,7 @@ int sqlite3_os_init(void){
     winRandomness,     /* xRandomness */
     winSleep,          /* xSleep */
     winCurrentTime,    /* xCurrentTime */
-    winGetLastError    /* xGetLastError */
-    0,                 /* xShmOpen */
-    0,                 /* xShmSize */
-    0,                 /* xShmPush */
-    0,                 /* xShmPull */
-    0,                 /* xShmLock */
-    0,                 /* xShmClose */
-    0,                 /* xShmDelete */
-    0,                 /* xRename */
-    0,                 /* xCurrentTimeInt64 */
+    winGetLastError,   /* xGetLastError */
   };
 
   sqlite3_vfs_register(&winVfs, 1);
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index f673781e0..7bc750944 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -844,7 +844,8 @@ struct sqlite3_vfs {
   ** definition.  Those that follow are added in version 2 or later
   */
   int (*xShmOpen)(sqlite3_vfs*, const char *zName, sqlite3_shm**);
-  int (*xShmSize)(sqlite3_shm*, int reqSize, int *pNewSize, char **);
+  int (*xShmSize)(sqlite3_shm*, int reqSize, int *pNewSize, char**);
+  int (*xShmRelease)(sqlite3_shm*);
   int (*xShmPush)(sqlite3_shm*);
   int (*xShmPull)(sqlite3_shm*);
   int (*xShmLock)(sqlite3_shm*, int lockType, int ofst, int nByte);
diff --git a/src/test6.c b/src/test6.c
index a6e995451..3da9502fd 100644
--- a/src/test6.c
+++ b/src/test6.c
@@ -782,15 +782,6 @@ static int crashEnableCmd(
     cfRandomness,         /* xRandomness */
     cfSleep,              /* xSleep */
     cfCurrentTime,        /* xCurrentTime */
-    0,                    /* xShmOpen */
-    0,                    /* xShmSize */
-    0,                    /* xShmPush */
-    0,                    /* xShmPull */
-    0,                    /* xShmLock */
-    0,                    /* xShmClose */
-    0,                    /* xShmDelete */
-    0,                    /* xRename */
-    0                     /* xCurrentTimeInt64 */
   };
 
   if( objc!=2 ){
diff --git a/src/test_demovfs.c b/src/test_demovfs.c
index d91a389db..7cdae8067 100644
--- a/src/test_demovfs.c
+++ b/src/test_demovfs.c
@@ -624,15 +624,6 @@ sqlite3_vfs *sqlite3_demovfs(void){
     demoRandomness,               /* xRandomness */
     demoSleep,                    /* xSleep */
     demoCurrentTime,              /* xCurrentTime */
-    0,                            /* xShmOpen */
-    0,                            /* xShmSize */
-    0,                            /* xShmPush */
-    0,                            /* xShmPull */
-    0,                            /* xShmLock */
-    0,                            /* xShmClose */
-    0,                            /* xShmDelete */
-    0,                            /* xRename */
-    0                             /* xCurrentTimeInt64 */
   };
   return &demovfs;
 }
diff --git a/src/test_devsym.c b/src/test_devsym.c
index 4249573aa..9f7153804 100644
--- a/src/test_devsym.c
+++ b/src/test_devsym.c
@@ -93,15 +93,6 @@ static sqlite3_vfs devsym_vfs = {
   devsymRandomness,         /* xRandomness */
   devsymSleep,              /* xSleep */
   devsymCurrentTime,        /* xCurrentTime */
-  0,                        /* xShmOpen */
-  0,                        /* xShmSize */
-  0,                        /* xShmPush */
-  0,                        /* xShmPull */
-  0,                        /* xShmLock */
-  0,                        /* xShmClose */
-  0,                        /* xShmDelete */
-  0,                        /* xRename */
-  0                         /* xCurrentTimeInt64 */
 };
 
 static sqlite3_io_methods devsym_io_methods = {
diff --git a/src/test_journal.c b/src/test_journal.c
index fcfe778d1..020b41575 100644
--- a/src/test_journal.c
+++ b/src/test_journal.c
@@ -180,15 +180,6 @@ static sqlite3_vfs jt_vfs = {
   jtRandomness,                  /* xRandomness */
   jtSleep,                       /* xSleep */
   jtCurrentTime,                 /* xCurrentTime */
-  0,                             /* xShmOpen */
-  0,                             /* xShmSize */
-  0,                             /* xShmPush */
-  0,                             /* xShmPull */
-  0,                             /* xShmLock */
-  0,                             /* xShmClose */
-  0,                             /* xShmDelete */
-  0,                             /* xRename */
-  0                              /* xCurrentTimeInt64 */
 };
 
 static sqlite3_io_methods jt_io_methods = {
diff --git a/src/test_osinst.c b/src/test_osinst.c
index c6d16aa67..365da38d8 100644
--- a/src/test_osinst.c
+++ b/src/test_osinst.c
@@ -204,15 +204,6 @@ static sqlite3_vfs inst_vfs = {
   instRandomness,         /* xRandomness */
   instSleep,              /* xSleep */
   instCurrentTime,        /* xCurrentTime */
-  0,                      /* xShmOpen */
-  0,                      /* xShmSize */
-  0,                      /* xShmPush */
-  0,                      /* xShmPull */
-  0,                      /* xShmLock */
-  0,                      /* xShmClose */
-  0,                      /* xShmDelete */
-  0,                      /* xRename */
-  0                       /* xCurrentTimeInt64 */
 };
 
 static sqlite3_io_methods inst_io_methods = {