Cause the mmap_size PRAGMA to immediately change the mmap space if the

database connection is already active.  In particular, reducing mmap_size
will immediately free up process address space.

FossilOrigin-Name: 761177927cb51e4f5e66061ca39cf37edbe8346b

2 files changed, 20 insertions, 6 deletions

diff --git a/src/os_unix.c b/src/os_unix.c
index abc23a452..242c2a3c3 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -3775,15 +3775,19 @@ static int unixFileControl(sqlite3_file *id, int op, void *pArg){
     }
     case SQLITE_FCNTL_MMAP_SIZE: {
       i64 newLimit = *(i64*)pArg;
+      int rc = SQLITE_OK;
       if( newLimit>sqlite3GlobalConfig.mxMmap ){
         newLimit = sqlite3GlobalConfig.mxMmap;
       }
       *(i64*)pArg = pFile->mmapSizeMax;
-      if( newLimit>=0 ){
+      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
         pFile->mmapSizeMax = newLimit;
-        if( newLimit<pFile->mmapSize ) pFile->mmapSize = newLimit;
+        if( pFile->mmapSize>0 ){
+          unixUnmapfile(pFile);
+          rc = unixMapfile(pFile, -1);
+        }
       }
-      return SQLITE_OK;
+      return rc;
     }
 #ifdef SQLITE_DEBUG
     /* The pager calls this method to signal that it has done
diff --git a/src/os_win.c b/src/os_win.c
index aeb08814b..07b74cbe2 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -2816,6 +2816,9 @@ static void winModeBit(winFile *pFile, unsigned char mask, int *pArg){
 
 /* Forward declaration */
 static int getTempname(int nBuf, char *zBuf);
+#if SQLITE_MAX_MMAP_SIZE>0
+static int winMapfile(winFile*, sqlite3_int64);
+#endif
 
 /*
 ** Control and query of the open file handle.
@@ -2899,13 +2902,20 @@ static int winFileControl(sqlite3_file *id, int op, void *pArg){
 #if SQLITE_MAX_MMAP_SIZE>0
     case SQLITE_FCNTL_MMAP_SIZE: {
       i64 newLimit = *(i64*)pArg;
+      int rc = SQLITE_OK;
       if( newLimit>sqlite3GlobalConfig.mxMmap ){
         newLimit = sqlite3GlobalConfig.mxMmap;
       }
       *(i64*)pArg = pFile->mmapSizeMax;
-      if( newLimit>=0 ) pFile->mmapSizeMax = newLimit;
-      OSTRACE(("FCNTL file=%p, rc=SQLITE_OK\n", pFile->h));
-      return SQLITE_OK;
+      if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){
+        pFile->mmapSizeMax = newLimit;
+        if( pFile->mmapSize>0 ){
+          (void)winUnmapfile(pFile);
+          rc = winMapfile(pFile, -1);
+        }
+      }
+      OSTRACE(("FCNTL file=%p, rc=%d\n", pFile->h, rc));
+      return rc;
     }
 #endif
   }