runtime: move init/shutdown into the "runtime"

Provide a mechanism for system components to register for initialization
and shutdown of the libgit2 runtime.

Author: ethomson

src/alloc.c

@@ -6,6 +6,7 @@
  */
 
 #include "alloc.h"
+#include "runtime.h"
 
 #include "allocators/stdalloc.h"
 #include "allocators/win32_crtdbg.h"
@@ -40,7 +41,8 @@ int git_allocator_global_init(void)
 	git_win32__crtdbg_stacktrace_init();
 	git_win32__stack_init();
 
-	git__on_shutdown(allocator_global_shutdown);
+	if (git_runtime_shutdown_register(allocator_global_shutdown) < 0)
+		return -1;
 #endif
 
 	/*

src/filter.c

@@ -11,7 +11,7 @@
 #include "futils.h"
 #include "hash.h"
 #include "repository.h"
-#include "global.h"
+#include "runtime.h"
 #include "git2/sys/filter.h"
 #include "git2/config.h"
 #include "blob.h"
@@ -206,7 +206,7 @@ int git_filter_global_init(void)
 			GIT_FILTER_IDENT, ident, GIT_FILTER_IDENT_PRIORITY) < 0)
 		error = -1;
 
-	git__on_shutdown(git_filter_global_shutdown);
+	error = git_runtime_shutdown_register(git_filter_global_shutdown);
 
 done:
 	if (error) {

src/futils.c

@@ -7,7 +7,7 @@
 
 #include "futils.h"
 
-#include "global.h"
+#include "runtime.h"
 #include "strmap.h"
 #include "hash.h"
 #include <ctype.h>

src/global.c

@@ -5,7 +5,7 @@
  * a Linking Exception. For full terms see the included COPYING file.
  */
 
-#include "global.h"
+#include "runtime.h"
 
 #include "alloc.h"
 #include "threadstate.h"
@@ -24,159 +24,29 @@
 #include "transports/ssh.h"
 #include "win32/w32_stack.h"
 
-typedef int (*git_global_init_fn)(void);
-
-static git_global_init_fn git__init_callbacks[] = {
-	git_allocator_global_init,
-	git_threadstate_global_init,
-	git_threads_global_init,
-	git_hash_global_init,
-	git_sysdir_global_init,
-	git_filter_global_init,
-	git_merge_driver_global_init,
-	git_transport_ssh_global_init,
-	git_stream_registry_global_init,
-	git_openssl_stream_global_init,
-	git_mbedtls_stream_global_init,
-	git_mwindow_global_init,
-	git_pool_global_init,
-	git_settings_global_init
-};
-
-static git_global_shutdown_fn git__shutdown_callbacks[ARRAY_SIZE(git__init_callbacks)];
-
-static git_atomic git__n_shutdown_callbacks;
-static git_atomic git__n_inits;
-
-void git__on_shutdown(git_global_shutdown_fn callback)
-{
-	int count = git_atomic_inc(&git__n_shutdown_callbacks);
-	assert(count <= (int) ARRAY_SIZE(git__shutdown_callbacks) && count > 0);
-	git__shutdown_callbacks[count - 1] = callback;
-}
-
-static int init_common(void)
-{
-	size_t i;
-	int ret;
-
-	/* Initialize subsystems that have global state */
-	for (i = 0; i < ARRAY_SIZE(git__init_callbacks); i++)
-		if ((ret = git__init_callbacks[i]()) != 0)
-			break;
-
-	GIT_MEMORY_BARRIER;
-
-	return ret;
-}
-
-static void shutdown_common(void)
-{
-	int pos;
-
-	/* Shutdown subsystems that have registered */
-	for (pos = git_atomic_get(&git__n_shutdown_callbacks);
-		pos > 0;
-		pos = git_atomic_dec(&git__n_shutdown_callbacks)) {
-
-		git_global_shutdown_fn cb = git__swap(
-			git__shutdown_callbacks[pos - 1], NULL);
-
-		if (cb != NULL)
-			cb();
-	}
-}
-
-/*
- * `git_libgit2_init()` allows subsystems to perform global setup,
- * which may take place in the global scope.  An explicit memory
- * fence exists at the exit of `git_libgit2_init()`.  Without this,
- * CPU cores are free to reorder cache invalidation of `_tls_init`
- * before cache invalidation of the subsystems' newly written global
- * state.
- */
-#if defined(GIT_THREADS) && defined(GIT_WIN32)
-
-/*
- * On Win32, we use a spinlock to provide locking semantics.  This is
- * lighter-weight than a proper critical section.
- */
-static volatile LONG init_spinlock = 0;
-
-GIT_INLINE(int) init_lock(void)
-{
-	while (InterlockedCompareExchange(&init_spinlock, 1, 0)) { Sleep(0); }
-	return 0;
-}
-
-GIT_INLINE(int) init_unlock(void)
-{
-	InterlockedExchange(&init_spinlock, 0);
-	return 0;
-}
-
-#elif defined(GIT_THREADS) && defined(_POSIX_THREADS)
-
-/*
- * On POSIX, we need to use a proper mutex for locking.  We might prefer
- * a spinlock here, too, but there's no static initializer for a
- * pthread_spinlock_t.
- */
-static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
-
-GIT_INLINE(int) init_lock(void)
-{
-	return pthread_mutex_lock(&mutex) == 0 ? 0 : -1;
-}
-
-GIT_INLINE(int) init_unlock(void)
-{
-	return pthread_mutex_unlock(&mutex) == 0 ? 0 : -1;
-}
-
-#elif defined(GIT_THREADS)
-# error unknown threading model
-#else
-
-# define init_lock() 0
-# define init_unlock() 0
-
-#endif
-
 int git_libgit2_init(void)
 {
-	int ret;
-
-	if (init_lock() < 0)
-		return -1;
-
-	/* Only do work on a 0 -> 1 transition of the refcount */
-	if ((ret = git_atomic_inc(&git__n_inits)) == 1) {
-		if (init_common() < 0)
-			ret = -1;
-	}
-
-	if (init_unlock() < 0)
-		return -1;
-
-	return ret;
+	static git_runtime_init_fn init_fns[] = {
+		git_allocator_global_init,
+		git_threadstate_global_init,
+		git_threads_global_init,
+		git_hash_global_init,
+		git_sysdir_global_init,
+		git_filter_global_init,
+		git_merge_driver_global_init,
+		git_transport_ssh_global_init,
+		git_stream_registry_global_init,
+		git_openssl_stream_global_init,
+		git_mbedtls_stream_global_init,
+		git_mwindow_global_init,
+		git_pool_global_init,
+		git_settings_global_init
+	};
+
+	return git_runtime_init(init_fns, ARRAY_SIZE(init_fns));
 }
 
 int git_libgit2_shutdown(void)
 {
-	int ret;
-
-	/* Enter the lock */
-	if (init_lock() < 0)
-		return -1;
-
-	/* Only do work on a 1 -> 0 transition of the refcount */
-	if ((ret = git_atomic_dec(&git__n_inits)) == 0)
-		shutdown_common();
-
-	/* Exit the lock */
-	if (init_unlock() < 0)
-		return -1;
-
-	return ret;
+	return git_runtime_shutdown();
 }

src/global.h

@@ -7,7 +7,7 @@
 
 #include "win32.h"
 
-#include "global.h"
+#include "runtime.h"
 
 #include <wincrypt.h>
 #include <strsafe.h>
@@ -129,7 +129,8 @@ int git_hash_sha1_global_init(void)
 	if ((error = hash_cng_prov_init()) < 0)
 		error = hash_cryptoapi_prov_init();
 
-	git__on_shutdown(sha1_shutdown);
+	if (!error)
+		error = git_runtime_shutdown_register(sha1_shutdown);
 
 	return error;
 }

src/hash/sha1/win32.c

@@ -8,7 +8,7 @@
 #include "merge_driver.h"
 
 #include "vector.h"
-#include "global.h"
+#include "runtime.h"
 #include "merge.h"
 #include "git2/merge.h"
 #include "git2/sys/merge.h"
@@ -209,7 +209,7 @@ int git_merge_driver_global_init(void)
 			merge_driver_name__binary, &git_merge_driver__binary)) < 0)
 		goto done;
 
-	git__on_shutdown(git_merge_driver_global_shutdown);
+	error = git_runtime_shutdown_register(git_merge_driver_global_shutdown);
 
 done:
 	if (error < 0)

src/merge_driver.c

@@ -10,7 +10,7 @@
 #include "vector.h"
 #include "futils.h"
 #include "map.h"
-#include "global.h"
+#include "runtime.h"
 #include "strmap.h"
 #include "pack.h"
 
@@ -50,14 +50,15 @@ static void git_mwindow_global_shutdown(void)
 
 int git_mwindow_global_init(void)
 {
-	assert(!git__pack_cache);
+	int error;
 
-	git__on_shutdown(git_mwindow_global_shutdown);
+	assert(!git__pack_cache);
 
-	if (git_mutex_init(&git__mwindow_mutex) != 0)
-		return -1;
+	if ((error = git_mutex_init(&git__mwindow_mutex)) < 0 ||
+	    (error = git_strmap_new(&git__pack_cache)) < 0)
+	    return error;
 
-	return git_strmap_new(&git__pack_cache);
+	return git_runtime_shutdown_register(git_mwindow_global_shutdown);
 }
 
 int git_mwindow_get_pack(struct git_pack_file **out, const char *path)

src/mwindow.c

@@ -14,7 +14,7 @@
 #include "posix.h"
 #include "buffer.h"
 #include "http_parser.h"
-#include "global.h"
+#include "runtime.h"
 
 #define DEFAULT_PORT_HTTP  "80"
 #define DEFAULT_PORT_HTTPS "443"

src/net.c

@@ -13,7 +13,7 @@
 #include "posix.h"
 #include "buffer.h"
 #include "http_parser.h"
-#include "global.h"
+#include "runtime.h"
 
 int gitno_recv(gitno_buffer *buf)
 {