Adding upstream version 3.2.6.upstream/3.2.6upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 133 insertions, 0 deletions

diff --git a/src/contrib/spinlock.h b/src/contrib/spinlock.h
new file mode 100644
index 0000000..837f500
--- /dev/null
+++ b/src/contrib/spinlock.h
@@ -0,0 +1,133 @@
+/*  Copyright (C) 2021 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Multiplatform spinlock.
+ */
+
+#pragma once
+
+#if (__STDC_VERSION__ >= 201112L) && !defined(__STDC_NO_ATOMICS__)
+/* Not tested and activated yet. */
+/* #define HAVE_STDATOMIC */
+#endif
+
+#if defined(__APPLE__)
+#  if defined(MAC_OS_X_VERSION_10_12) || \
+      MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12
+#    define APPLE_SPIN_NEW
+#  else
+#    define APPLE_SPIN_OLD
+#  endif	/* MAC_OS_X_VERSION_10_12 ... */
+#endif	/* __APPLE__ */
+
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC)
+#  include <stdbool.h>
+#elif defined(HAVE_STDATOMIC)
+#  include <stdbool.h>
+#  include <stdatomic.h>
+#elif defined(APPLE_SPIN_NEW)
+#  include <os/lock.h>
+#elif defined(APPLE_SPIN_OLD)
+#  include <libkern/OSAtomic.h>
+#else	/* POSIX pthread spinlock. */
+#  include <pthread.h>
+#endif
+
+/*! \brief Spinlock lock variable type. */
+typedef
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC)
+	bool			/*!< Spinlock lock - a simple & fast atomic version. */
+#elif defined(HAVE_STDATOMIC)
+	atomic_bool		/*!< Spinlock lock - a simple & fast atomic version, C11 */
+#elif defined(APPLE_SPIN_NEW)
+	os_unfair_lock		/*!< Spinlock lock - a newer macOS version (macOS >= 10.12). */
+#elif defined(APPLE_SPIN_OLD)
+	OSSpinLock		/*!< Spinlock lock - an older macOS version (macOS < 10.12). */
+#else	/* POSIX */
+	pthread_spinlock_t	/*!< Spinlock lock - a POSIX pthread version. */
+#endif
+	knot_spin_t;
+
+/*! \brief Initialize the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_init(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC)
+	*lock = false;
+#elif defined(HAVE_STDATOMIC)
+	atomic_init(lock, false);
+#elif defined(APPLE_SPIN_NEW)
+	*lock = OS_UNFAIR_LOCK_INIT;
+#elif defined(APPLE_SPIN_OLD)
+	*lock = OS_SPINLOCK_INIT;
+#else	/* POSIX */
+	pthread_spin_init(lock, PTHREAD_PROCESS_PRIVATE);
+#endif
+}
+
+/*! \brief Destroy the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_destroy(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC) || defined(HAVE_STDATOMIC) || \
+    defined(APPLE_SPIN_NEW) || defined(APPLE_SPIN_OLD)
+	/* Nothing needed here. */
+#else	/* POSIX */
+	pthread_spin_destroy(lock);
+#endif
+}
+
+/*! \brief Lock the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_lock(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC)
+	while (__sync_lock_test_and_set(lock, 1)) {
+	}
+#elif defined(HAVE_ATOMIC)
+	int expected = 0;
+        while (!__atomic_compare_exchange_n(lock, &expected, 1, false, __ATOMIC_RELAXED, __ATOMIC_RELAXED)) {
+		expected = 0;
+	}
+#elif defined(HAVE_STDATOMIC)
+	int expected = 0;
+	while (!atomic_compare_exchange_strong(lock, &expected, false)) {
+		expected = 0;
+	}
+#elif defined(APPLE_SPIN_NEW)
+	os_unfair_lock_lock(lock);
+#elif defined(APPLE_SPIN_OLD)
+	OSSpinLockLock(lock);
+#else	/* POSIX */
+	pthread_spin_lock(lock);
+#endif
+}
+
+/*! \brief Unlock the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_unlock(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC)
+	__sync_lock_release(lock);
+#elif defined(HAVE_ATOMIC)
+	__atomic_clear(lock, __ATOMIC_RELAXED);
+#elif defined(HAVE_STDATOMIC)
+	atomic_store(lock, false);
+#elif defined(APPLE_SPIN_NEW)
+	os_unfair_lock_unlock(lock);
+#elif defined(APPLE_SPIN_OLD)
+	OSSpinLockUnlock(lock);
+#else	/* POSIX */
+	pthread_spin_unlock(lock);
+#endif
+}