Question

I am using the zlib C library to decompress data received from a network stream, and I have two streams running in two separate NSThreads. As per zlib documentation, decompressing two different zlib streams in two threads requires zalloc and zfree to be thread safe. I am currently passing Z_NULL (my inflateinit code below)

zStream.zalloc = Z_NULL;
zStream.zfree = Z_NULL;
zStream.opaque = Z_NULL;
zStream.avail_in = 0;
zStream.next_in = Z_NULL;
int status = inflateInit(&zStream);
if (status != Z_OK)
    DLog(@"zlib setup error");
else
    DLog(@"zlib setup ok");
});

Does anyone have experience with using zlib for compressing multiple streams in separate threads? Has anyone seen a thread safe implementation of zalloc and zfree?

Answer 1

malloc() and free() on Mac OS X are already thread safe. So just initialize the structure with Z_NULL as you’re doing and you’ll be fine.