Bug 666611 - Do not set chunksize if less than 100MiB of storage is available. r=mak

storage/public/mozIStorageConnection.idl

@@ -361,13 +361,17 @@ interface mozIStorageConnection : nsISupports {
 
   /**
    * Controls SQLITE_FCNTL_CHUNK_SIZE setting in sqlite. This helps avoid fragmentation
-   * by growing/shrinking the database file in SQLITE_FCNTL_CHUNK_SIZE increments.
+   * by growing/shrinking the database file in SQLITE_FCNTL_CHUNK_SIZE increments. To
+   * conserve memory on systems short on storage space, this function will have no effect
+   * on mobile devices or if less than 100MB of space is left available.
    *
    * @param aIncrement
    *        The database file will grow in multiples of chunkSize.
    * @param aDatabaseName
    *        Sqlite database name. "" means pass NULL for zDbName to sqlite3_file_control.
    *        See http://sqlite.org/c3ref/file_control.html for more details.
+   * @throws NS_ERROR_FILE_TOO_BIG
+   *         If the system is short on storage space.
    */
   void setGrowthIncrement(in PRInt32 aIncrement, in AUTF8String aDatabaseName);
 };

storage/src/mozStorageConnection.cpp

@@ -47,9 +47,9 @@
 #include "nsIMutableArray.h"
 #include "nsHashSets.h"
 #include "nsAutoPtr.h"
-#include "nsIFile.h"
 #include "nsIMemoryReporter.h"
 #include "nsThreadUtils.h"
+#include "nsILocalFile.h"
 
 #include "mozIStorageAggregateFunction.h"
 #include "mozIStorageCompletionCallback.h"
@@ -70,6 +70,8 @@
 #include "prlog.h"
 #include "prprf.h"
 
+#define BYTES_PER_MEBIBYTE 1048576
+
 #ifdef PR_LOGGING
 PRLogModuleInfo* gStorageLog = nsnull;
 #endif
@@ -1245,6 +1247,16 @@ Connection::SetGrowthIncrement(PRInt32 aChunkSize, const nsACString &aDatabaseNa
   // so don't preallocate space. This is also not effective
   // on log structured file systems used by Android devices
 #if !defined(ANDROID) && !defined(MOZ_PLATFORM_MAEMO)
+  // Don't preallocate if less than 100MiB is available.
+  nsCOMPtr<nsILocalFile> localFile = do_QueryInterface(mDatabaseFile);
+  NS_ENSURE_STATE(localFile);
+  PRInt64 bytesAvailable;
+  nsresult rv = localFile->GetDiskSpaceAvailable(&bytesAvailable);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (bytesAvailable < 100 * BYTES_PER_MEBIBYTE) {
+    return NS_ERROR_FILE_TOO_BIG;
+  }
+
   (void)::sqlite3_file_control(mDBConn,
                                aDatabaseName.Length() ? nsPromiseFlatCString(aDatabaseName).get() : NULL,
                                SQLITE_FCNTL_CHUNK_SIZE,