We need to set the attributes before we try to insert it into the vector, as the comparison function needs to know whether the entry is a tree or not.
By inserting in the right position, we can keep the vector sorted, making entry insertion almost twice as fast.
This updates the git_pqueue to simply be a set of specialized init/insert/pop functions on a git_vector. To preserve the pqueue feature of having a fixed size heap, I converted the "sorted" field in git_vectors to a more general "flags" field so that pqueue could mix in it's own flag. This had a bunch of ramifications because a number of places were directly looking at the vector "sorted" field - I added a couple new git_vector helpers (is_sorted, set_sorted) so the specific representation of this information could be abstracted.
Rename git_tree_entry_byoid() to _byid() as per the convention.
This was not converted when we converted the rest, so do it now.
This changes the behavior of callbacks so that the callback error code is not converted into GIT_EUSER and instead we propagate the return value through to the caller. Instead of using the giterr_capture and giterr_restore functions, we now rely on all functions to pass back the return value from a callback. To avoid having a return value with no error message, the user can call the public giterr_set_str or some such function to set an error message. There is a new helper 'giterr_set_callback' that functions can invoke after making a callback which ensures that some error message was set in case the callback did not set one. In places where the sign of the callback return value is meaningful (e.g. positive to skip, negative to abort), only the negative values are returned back to the caller, obviously, since the other values allow for continuing the loop. The hardest parts of this were in the checkout code where positive return values were overloaded as meaningful values for checkout. I fixed this by adding an output parameter to many of the internal checkout functions and removing the overload. This added some code, but it is probably a better implementation. There is some funkiness in the network code where user provided callbacks could be returning a positive or a negative value and we want to rely on that to cancel the loop. There are still a couple places where an user error might get turned into GIT_EUSER there, I think, though none exercised by the tests.
This continues auditing all the places where GIT_EUSER is being returned and making sure to clear any existing error using the new giterr_user_cancel helper. As a result, places that relied on intercepting GIT_EUSER but having the old error preserved also needed to be cleaned up to correctly stash and then retrieve the actual error. Additionally, as I encountered places where error codes were not being propagated correctly, I tried to fix them up. A number of those fixes are included in the this commit as well.
When a tool needs to recreate the tree object (for example an interface to another VCS), it needs to use the raw attributes, forgoing any normalization.