runtime: move init/shutdown into the "runtime"

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

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

-/*
- * Copyright (C) the libgit2 contributors. All rights reserved.
- *
- * This file is part of libgit2, distributed under the GNU GPL v2 with
- * a Linking Exception. For full terms see the included COPYING file.
- */
-#ifndef INCLUDE_global_h__
-#define INCLUDE_global_h__
-
-#include "common.h"
-
-typedef void (*git_global_shutdown_fn)(void);
-
-extern void git__on_shutdown(git_global_shutdown_fn callback);
-
-#endif

src/hash/sha1/win32.c

@@ -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/merge_driver.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/mwindow.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/net.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/netops.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)
 {

src/runtime.c

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "common.h"
+#include "runtime.h"
+
+static git_runtime_shutdown_fn shutdown_callback[32];
+static git_atomic shutdown_callback_count;
+
+static git_atomic init_count;
+
+static int init_common(git_runtime_init_fn init_fns[], size_t cnt)
+{
+	size_t i;
+	int ret;
+
+	/* Initialize subsystems that have global state */
+	for (i = 0; i < cnt; i++) {
+		if ((ret = init_fns[i]()) != 0)
+			break;
+	}
+
+	GIT_MEMORY_BARRIER;
+
+	return ret;
+}
+
+static void shutdown_common(void)
+{
+	git_runtime_shutdown_fn cb;
+	int pos;
+
+	for (pos = git_atomic_get(&shutdown_callback_count);
+	     pos > 0;
+	     pos = git_atomic_dec(&shutdown_callback_count)) {
+		cb = git__swap(shutdown_callback[pos - 1], NULL);
+
+		if (cb != NULL)
+			cb();
+	}
+}
+
+int git_runtime_shutdown_register(git_runtime_shutdown_fn callback)
+{
+	int count = git_atomic_inc(&shutdown_callback_count);
+
+	if (count > (int)ARRAY_SIZE(shutdown_callback) || count == 0) {
+		git_error_set(GIT_ERROR_INVALID,
+		              "too many shutdown callbacks registered");
+		git_atomic_dec(&shutdown_callback_count);
+		return -1;
+	}
+
+	shutdown_callback[count - 1] = callback;
+
+	return 0;
+}
+
+#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 init_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+GIT_INLINE(int) init_lock(void)
+{
+	return pthread_mutex_lock(&init_mutex) == 0 ? 0 : -1;
+}
+
+GIT_INLINE(int) init_unlock(void)
+{
+	return pthread_mutex_unlock(&init_mutex) == 0 ? 0 : -1;
+}
+
+#elif defined(GIT_THREADS)
+# error unknown threading model
+#else
+
+# define mutex_lock() 0
+# define mutex_unlock() 0
+
+#endif
+
+int git_runtime_init(git_runtime_init_fn init_fns[], size_t cnt)
+{
+	int ret;
+
+	if (init_lock() < 0)
+		return -1;
+
+	/* Only do work on a 0 -> 1 transition of the refcount */
+	if ((ret = git_atomic_inc(&init_count)) == 1) {
+		if (init_common(init_fns, cnt) < 0)
+			ret = -1;
+	}
+
+	if (init_unlock() < 0)
+		return -1;
+
+	return ret;
+}
+
+int git_runtime_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(&init_count)) == 0)
+		shutdown_common();
+
+	/* Exit the lock */
+	if (init_unlock() < 0)
+		return -1;
+
+	return ret;
+}

src/runtime.h

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_runtime_h__
+#define INCLUDE_runtime_h__
+
+#include "common.h"
+
+typedef int (*git_runtime_init_fn)(void);
+typedef void (*git_runtime_shutdown_fn)(void);
+
+/**
+ * Start up a new runtime.  If this is the first time that this
+ * function is called within the context of the current library
+ * or executable, then the given `init_fns` will be invoked.  If
+ * it is not the first time, they will be ignored.
+ *
+ * The given initialization functions _may_ register shutdown
+ * handlers using `git_runtime_shutdown_register` to be notified
+ * when the runtime is shutdown.
+ *
+ * @param init_fns The list of initialization functions to call
+ * @param cnt The number of init_fns
+ * @return The number of initializations performed (including this one) or an error
+ */
+int git_runtime_init(git_runtime_init_fn init_fns[], size_t cnt);
+
+/**
+ * Shut down the runtime.  If this is the last shutdown call,
+ * such that there are no remaining `init` calls, then any
+ * shutdown hooks that have been registered will be invoked.
+ *
+ * The number of oustanding initializations will be returned.
+ * If this number is 0, then the runtime is shutdown.
+ *
+ * @return The number of outstanding initializations (after this one) or an error
+ */
+int git_runtime_shutdown(void);
+
+/**
+ * Register a shutdown handler for this runtime.  This should be done
+ * by a function invoked by `git_runtime_init` to ensure that the
+ * appropriate locks are taken.
+ *
+ * @param callback The shutdown handler callback
+ * @return 0 or an error code
+ */
+int git_runtime_shutdown_register(git_runtime_shutdown_fn callback);
+
+#endif

src/settings.c

@@ -19,7 +19,7 @@
 #include "alloc.h"
 #include "sysdir.h"
 #include "cache.h"
-#include "global.h"
+#include "runtime.h"
 #include "object.h"
 #include "odb.h"
 #include "refs.h"
@@ -47,8 +47,7 @@ static void git_settings_global_shutdown(void)
 
 int git_settings_global_init(void)
 {
-	git__on_shutdown(git_settings_global_shutdown);
-	return 0;
+	return git_runtime_shutdown_register(git_settings_global_shutdown);
 }
 
 int git_libgit2_version(int *major, int *minor, int *rev)

src/streams/mbedtls.c

@@ -11,7 +11,7 @@
 
 #include <ctype.h>
 
-#include "global.h"
+#include "runtime.h"
 #include "stream.h"
 #include "streams/socket.h"
 #include "netops.h"
@@ -152,9 +152,7 @@ int git_mbedtls_stream_global_init(void)
 	if (!loaded && crtpath != NULL && stat(crtpath, &statbuf) == 0 && S_ISDIR(statbuf.st_mode))
 		loaded = (git_mbedtls__set_cert_location(crtpath, 1) == 0);
 
-	git__on_shutdown(shutdown_ssl);
-
-	return 0;
+	return git_runtime_shutdown_register(shutdown_ssl);
 
 cleanup:
 	mbedtls_ctr_drbg_free(ctr_drbg);

src/streams/openssl.c

@@ -11,7 +11,7 @@
 
 #include <ctype.h>
 
-#include "global.h"
+#include "runtime.h"
 #include "settings.h"
 #include "posix.h"
 #include "stream.h"
@@ -286,9 +286,7 @@ int git_openssl_stream_global_init(void)
 	if (init_bio_method() < 0)
 		goto error;
 
-	git__on_shutdown(shutdown_ssl);
-
-	return 0;
+	return git_runtime_shutdown_register(shutdown_ssl);
 
 error:
 	git_error_set(GIT_ERROR_NET, "could not initialize openssl: %s",
@@ -325,8 +323,8 @@ int git_openssl_set_locking(void)
 	}
 
 	CRYPTO_set_locking_callback(openssl_locking_function);
-	git__on_shutdown(shutdown_ssl_locking);
-	return 0;
+	return git_runtime_shutdown_register(shutdown_ssl_locking);
+
 #elif !defined(OPENSSL_LEGACY_API)
 	return 0;
 #else

src/streams/registry.c

@@ -9,7 +9,7 @@
 
 #include "streams/registry.h"
 
-#include "global.h"
+#include "runtime.h"
 #include "streams/tls.h"
 #include "streams/mbedtls.h"
 #include "streams/openssl.h"
@@ -33,8 +33,7 @@ int git_stream_registry_global_init(void)
 	if (git_rwlock_init(&stream_registry.lock) < 0)
 		return -1;
 
-	git__on_shutdown(shutdown_stream_registry);
-	return 0;
+	return git_runtime_shutdown_register(shutdown_stream_registry);
 }
 
 GIT_INLINE(void) stream_registration_cpy(

src/streams/tls.c

@@ -8,7 +8,6 @@
 #include "git2/errors.h"
 
 #include "common.h"
-#include "global.h"
 #include "streams/registry.h"
 #include "streams/tls.h"
 #include "streams/mbedtls.h"

src/sysdir.c

@@ -7,7 +7,7 @@
 
 #include "sysdir.h"
 
-#include "global.h"
+#include "runtime.h"
 #include "buffer.h"
 #include "path.h"
 #include <ctype.h>
@@ -189,9 +189,7 @@ int git_sysdir_global_init(void)
 	for (i = 0; !error && i < ARRAY_SIZE(git_sysdir__dirs); i++)
 		error = git_sysdir__dirs[i].guess(&git_sysdir__dirs[i].buf);
 
-	git__on_shutdown(git_sysdir_global_shutdown);
-
-	return error;
+	return git_runtime_shutdown_register(git_sysdir_global_shutdown);
 }
 
 static int git_sysdir_check_selector(git_sysdir_t which)

src/threadstate.c

@@ -6,7 +6,7 @@
  */
 
 #include "threadstate.h"
-#include "global.h"
+#include "runtime.h"
 
 static void threadstate_dispose(git_threadstate *threadstate);
 
@@ -57,9 +57,7 @@ int git_threadstate_global_init(void)
 	if ((fls_index = FlsAlloc(fls_free)) == FLS_OUT_OF_INDEXES)
 		return -1;
 
-	git__on_shutdown(git_threadstate_global_shutdown);
-
-	return 0;
+	return git_runtime_shutdown_register(git_threadstate_global_shutdown);
 }
 
 git_threadstate *git_threadstate_get(void)
@@ -105,9 +103,7 @@ int git_threadstate_global_init(void)
 	if (pthread_key_create(&tls_key, &tls_free) != 0)
 		return -1;
 
-	git__on_shutdown(git_threadstate_global_shutdown);
-
-	return 0;
+	return git_runtime_shutdown_register(git_threadstate_global_shutdown);
 }
 
 git_threadstate *git_threadstate_get(void)
@@ -134,14 +130,12 @@ static git_threadstate threadstate;
 static void git_threadstate_global_shutdown(void)
 {
 	threadstate_dispose(&threadstate);
-	memset(&threadstate, 0, sizeof(git_threadstate);
+	memset(&threadstate, 0, sizeof(git_threadstate));
 }
 
 int git_threadstate_global_init(void)
 {
-	git__on_shutdown(git_threadstate_global_shutdown);
-
-	return 0;
+	return git_runtime_shutdown_register(git_tlsdata_global_shutdown);
 }
 
 git_threadstate *git_threadstate_get(void)

src/trace.c

@@ -8,7 +8,7 @@
 #include "trace.h"
 
 #include "buffer.h"
-#include "global.h"
+#include "runtime.h"
 #include "git2/trace.h"
 
 #ifdef GIT_TRACE

src/transports/http.c

@@ -14,7 +14,6 @@
 #include "buffer.h"
 #include "net.h"
 #include "netops.h"
-#include "global.h"
 #include "remote.h"
 #include "git2/sys/credential.h"
 #include "smart.h"

src/transports/httpclient.c

@@ -10,7 +10,6 @@
 #include "http_parser.h"
 #include "vector.h"
 #include "trace.h"
-#include "global.h"
 #include "httpclient.h"
 #include "http.h"
 #include "auth.h"

src/transports/ssh.c

@@ -11,7 +11,7 @@
 #include <libssh2.h>
 #endif
 
-#include "global.h"
+#include "runtime.h"
 #include "git2.h"
 #include "buffer.h"
 #include "net.h"
@@ -934,8 +934,7 @@ int git_transport_ssh_global_init(void)
 		return -1;
 	}
 
-	git__on_shutdown(shutdown_ssh);
-	return 0;
+	return git_runtime_shutdown_register(shutdown_ssh);
 
 #else
 

src/transports/winhttp.c

@@ -17,7 +17,6 @@
 #include "smart.h"
 #include "remote.h"
 #include "repository.h"
-#include "global.h"
 #include "http.h"
 #include "git2/sys/credential.h"
 

src/win32/posix_w32.c

@@ -14,7 +14,6 @@
 #include "utf-conv.h"
 #include "repository.h"
 #include "reparse.h"
-#include "global.h"
 #include "buffer.h"
 #include <errno.h>
 #include <io.h>

src/win32/thread.c

@@ -6,6 +6,7 @@
  */
 
 #include "thread.h"
+#include "runtime.h"
 
 #define CLEAN_THREAD_EXIT 0x6F012842
 
@@ -60,9 +61,7 @@ int git_threads_global_init(void)
 	if ((fls_index = FlsAlloc(NULL)) == FLS_OUT_OF_INDEXES)
 		return -1;
 
-	git__on_shutdown(git_threads_global_shutdown);
-
-	return 0;
+	return git_runtime_shutdown_register(git_threads_global_shutdown);
 }
 
 int git_thread_create(

tests/pack/filelimit.c

 #include "clar_libgit2.h"
 #include "mwindow.h"
-#include "global.h"
 
 #include <git2.h>
 #include "git2/sys/commit.h"