diff options
Diffstat (limited to 'Minecraft.World/CompressedTileStorage.cpp')
| -rw-r--r-- | Minecraft.World/CompressedTileStorage.cpp | 45 |
1 files changed, 33 insertions, 12 deletions
diff --git a/Minecraft.World/CompressedTileStorage.cpp b/Minecraft.World/CompressedTileStorage.cpp index eb1b784a..5ba46dee 100644 --- a/Minecraft.World/CompressedTileStorage.cpp +++ b/Minecraft.World/CompressedTileStorage.cpp @@ -146,7 +146,9 @@ CompressedTileStorage::CompressedTileStorage(bool isEmpty) bool CompressedTileStorage::isRenderChunkEmpty(int y) // y == 0, 16, 32... 112 (representing a 16 byte range) { int block; - unsigned short *blockIndices = (unsigned short *)indicesAndData; + unsigned char *localIndicesAndData = indicesAndData; + if(!localIndicesAndData) return true; + unsigned short *blockIndices = (unsigned short *)localIndicesAndData; for( int x = 0; x < 16; x += 4 ) for( int z = 0; z < 16; z += 4 ) @@ -533,8 +535,12 @@ void CompressedTileStorage::getData(byteArray retArray, unsigned int retOffset) // Gets all tile values into an array of length 32768. void CompressedTileStorage::getData(byteArray retArray, unsigned int retOffset) { - unsigned short *blockIndices = (unsigned short *)indicesAndData; - unsigned char *data = indicesAndData + 1024; + // Snapshot pointer to avoid race with compress() swapping indicesAndData + unsigned char *localIndicesAndData = indicesAndData; + if(!localIndicesAndData) return; + + unsigned short *blockIndices = (unsigned short *)localIndicesAndData; + unsigned char *data = localIndicesAndData + 1024; for( int i = 0; i < 512; i++ ) { @@ -588,10 +594,13 @@ void CompressedTileStorage::getData(byteArray retArray, unsigned int retOffset) // Get an individual tile value int CompressedTileStorage::get(int x, int y, int z) { - if(!indicesAndData) return 0; + // Take a local snapshot of indicesAndData to avoid a race with compress() which swaps the pointer. + // Both blockIndices and data must reference the same buffer, otherwise index offsets won't match. + unsigned char *localIndicesAndData = indicesAndData; + if(!localIndicesAndData) return 0; - unsigned short *blockIndices = (unsigned short *)indicesAndData; - unsigned char *data = indicesAndData + 1024; + unsigned short *blockIndices = (unsigned short *)localIndicesAndData; + unsigned char *data = localIndicesAndData + 1024; int block, tile; getBlockAndTile( &block, &tile, x, y, z ); @@ -1223,7 +1232,10 @@ int CompressedTileStorage::getAllocatedSize(int *count0, int *count1, int *count *count4 = 0; *count8 = 0; - unsigned short *blockIndices = (unsigned short *)indicesAndData; + // Volatile read: compress() can swap indicesAndData concurrently outside cs_write + unsigned char *localIndicesAndData = *(unsigned char *volatile *)&indicesAndData; + if(!localIndicesAndData) return 0; + unsigned short *blockIndices = (unsigned short *)localIndicesAndData; for(int i = 0; i < 512; i++ ) { unsigned short idxType = blockIndices[i] & INDEX_TYPE_MASK; @@ -1256,7 +1268,9 @@ int CompressedTileStorage::getAllocatedSize(int *count0, int *count1, int *count int CompressedTileStorage::getHighestNonEmptyY() { - unsigned short *blockIndices = (unsigned short *)indicesAndData; + unsigned char *localIndicesAndData = indicesAndData; + if(!localIndicesAndData) return -1; + unsigned short *blockIndices = (unsigned short *)localIndicesAndData; unsigned int highestYBlock = 0; bool found = false; @@ -1297,19 +1311,26 @@ int CompressedTileStorage::getHighestNonEmptyY() // Multiply by the number of vertical tiles in a block, and then add that again to be at the top of the block highestNonEmptyY = (highestYBlock * 4) + 4; } + else + { + app.DebugPrintf("[CTS-WARN] getHighestNonEmptyY() returned -1! allocatedSize=%d indicesAndData=%p\n", + allocatedSize, indicesAndData); + } return highestNonEmptyY; } void CompressedTileStorage::write(DataOutputStream *dos) { dos->writeInt(allocatedSize); - if(indicesAndData) + // Volatile read: compress() can swap indicesAndData concurrently outside cs_write + unsigned char *localIndicesAndData = *(unsigned char *volatile *)&indicesAndData; + if(localIndicesAndData) { if(LOCALSYTEM_ENDIAN == BIGENDIAN) { // The first 1024 bytes are an array of shorts, so we need to reverse the endianness byteArray indicesCopy(1024); - memcpy(indicesCopy.data, indicesAndData, 1024); + memcpy(indicesCopy.data, localIndicesAndData, 1024); reverseIndices(indicesCopy.data); dos->write(indicesCopy); delete [] indicesCopy.data; @@ -1317,13 +1338,13 @@ void CompressedTileStorage::write(DataOutputStream *dos) // Write the rest of the data if(allocatedSize > 1024) { - byteArray dataWrapper(indicesAndData + 1024, allocatedSize - 1024); + byteArray dataWrapper(localIndicesAndData + 1024, allocatedSize - 1024); dos->write(dataWrapper); } } else { - byteArray wrapper(indicesAndData, allocatedSize); + byteArray wrapper(localIndicesAndData, allocatedSize); dos->write(wrapper); } } |