Shutdown callback count #4919
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Shutdown callback count #4919
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The `git_hash_global_init` function is simply defined as a macro to zero for most of the different hash implementations. This makes it impossible to treat it like a function pointer, which is required for a later commit where we want to improve the way global initialization works. Fix the issue by converting all no-op macros to an inline function returning zero. There's a small gotcha here, though: as most hash implementations only have a header file, but not a corresponding implementation file, we cannot declare the function as non-static. But declaring it as `static inline` fails, too, as there is a previous declaration as non-static. So we have to move the function declaration after the include that brings in the function definition, as it is allowed to have a non-static declaration after a static definition, but not the other way round.
We currently have an explicit callchain of all the initialization callbacks in our `init_common` function. This is perfectly fine, but requires us to manually keep track of how many shutdown callbacks there may be installed: to avoid allocations before libgit2 is fully initialized, we assume that every initializer may register at most one shutdown function. These shutdown functions are stored in a static array of size `MAX_SHUTDOWN_CB`, which then needs to be updated manually whenever a new initializer function is being added. The situation can be easily fixed: convert the callchain of init functions into an array and iterate over it to initialize all subsystems. This allows us to define the `git__shutdown_callbacks` array with the same size as the initializer array and rids us of the need to always update `MAX_SHUTDOWN_CB`.
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It randomly occurred to me that we can avoid manually updating the
MAX_SHUTDOWN_CBmacro whenever we add a new global initializer by just declaring the initializers as an array and then using the initializer array's size to declare the shutdown array. This PR does exactly that as a small cleanup.