Set a message when we fail to lock. Also make the put function void, since it's called from free, which cannot report errors. The only errors we can experience here are internal state corruption, so we assert that we are trying to put a pack which we have previously got.
If we fail to insert the packfile in the map, make sure to free it. This makes the free function only attempt to remove its mwindows from the global list if we have opened the packfile to avoid accessing the list unlocked.
Opening the same repository multiple times will currently open the same file multiple times, as well as map the same region of the file multiple times. This is not necessary, as the packfile data is immutable. Instead of opening and closing packfiles directly, introduce an indirection and allocate packfiles globally. This does mean locking on each packfile open, but we already use this lock for the global mwindow list so it doesn't introduce a new contention point.
This builds on the earlier thread safety work to make it so that setting the odb, index, refdb, or config for a repository is done in a threadsafe manner with minimized locking time. This is done by adding a lock to the repository object and using it to guard the assignment of the above listed pointers. The lock is only held to assign the pointer value. This also contains some minor fixes to the other work with pack files to reduce the time that locks are being held to and fix an apparently memory leak.
Implicit type conversion argument of function to size_t type Suspicious sequence of types castings: size_t -> int -> size_t Consider reviewing the expression of the 'A = B == C' kind. The expression is calculated as following: 'A = (B == C)' Unsigned type is never < 0
As a function that appears to only be called on error paths, I don't think it makes sense for it to return an error, or clobber the global giterr. Note that no existing callsites actually check the return code. In my own application, there are errors where the real error ends up being hidden, as git_mwindow_file_deregister() clobbers the global giterr. I'm not sure this error is even relevant?