MINOR: threads: Add atomic-ops and plock includes in import dir
atomic-ops header contains some low-level functions to do atomic
operations. These operations are used by the progressive locks (plock).
diff --git a/include/import/plock.h b/include/import/plock.h
new file mode 100644
index 0000000..5f23f22
--- /dev/null
+++ b/include/import/plock.h
@@ -0,0 +1,427 @@
+/* plock - progressive locks
+ *
+ * Copyright (C) 2012-2017 Willy Tarreau <w@1wt.eu>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "atomic-ops.h"
+
+/* 64 bit */
+#define PLOCK64_RL_1 0x0000000000000004ULL
+#define PLOCK64_RL_ANY 0x00000000FFFFFFFCULL
+#define PLOCK64_SL_1 0x0000000100000000ULL
+#define PLOCK64_SL_ANY 0x0000000300000000ULL
+#define PLOCK64_WL_1 0x0000000400000000ULL
+#define PLOCK64_WL_ANY 0xFFFFFFFC00000000ULL
+
+/* 32 bit */
+#define PLOCK32_RL_1 0x00000004
+#define PLOCK32_RL_ANY 0x0000FFFC
+#define PLOCK32_SL_1 0x00010000
+#define PLOCK32_SL_ANY 0x00030000
+#define PLOCK32_WL_1 0x00040000
+#define PLOCK32_WL_ANY 0xFFFC0000
+
+/* dereferences <*p> as unsigned long without causing aliasing issues */
+#define pl_deref_long(p) ({ volatile unsigned long *__plock_l = (void *)(p); *__plock_l; })
+
+/* dereferences <*p> as unsigned int without causing aliasing issues */
+#define pl_deref_int(p) ({ volatile unsigned int *__plock_i = (void *)(p); *__plock_i; })
+
+/* request shared read access (R), return non-zero on success, otherwise 0 */
+#define pl_try_r(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_deref_long(lock) & PLOCK64_WL_ANY; \
+ pl_barrier(); \
+ if (!__builtin_expect(ret, 0)) { \
+ ret = pl_xadd((lock), PLOCK64_RL_1) & PLOCK64_WL_ANY; \
+ if (__builtin_expect(ret, 0)) \
+ pl_sub((lock), PLOCK64_RL_1); \
+ } \
+ !ret; /* return value */ \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_deref_int(lock) & PLOCK32_WL_ANY; \
+ pl_barrier(); \
+ if (!__builtin_expect(ret, 0)) { \
+ ret = pl_xadd((lock), PLOCK32_RL_1) & PLOCK32_WL_ANY; \
+ if (__builtin_expect(ret, 0)) \
+ pl_sub((lock), PLOCK32_RL_1); \
+ } \
+ !ret; /* return value */ \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_try_r__(char *,int); \
+ __unsupported_argument_size_for_pl_try_r__(__FILE__,__LINE__); \
+ 0; \
+ }) \
+)
+
+/* request shared read access (R) and wait for it */
+#define pl_take_r(lock) \
+ do { \
+ while (__builtin_expect(pl_try_r(lock), 1) == 0) \
+ pl_cpu_relax(); \
+ } while (0)
+
+/* release the read access (R) lock */
+#define pl_drop_r(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_RL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_RL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_drop_r__(char *,int); \
+ __unsupported_argument_size_for_pl_drop_r__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* request a seek access (S), return non-zero on success, otherwise 0 */
+#define pl_try_s(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_deref_long(lock); \
+ pl_barrier(); \
+ if (!__builtin_expect(ret & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
+ ret = pl_xadd((lock), PLOCK64_SL_1 | PLOCK64_RL_1) & \
+ (PLOCK64_WL_ANY | PLOCK64_SL_ANY); \
+ if (__builtin_expect(ret, 0)) \
+ pl_sub((lock), PLOCK64_SL_1 | PLOCK64_RL_1); \
+ } \
+ !ret; /* return value */ \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_deref_int(lock); \
+ pl_barrier(); \
+ if (!__builtin_expect(ret & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
+ ret = pl_xadd((lock), PLOCK32_SL_1 | PLOCK32_RL_1) & \
+ (PLOCK32_WL_ANY | PLOCK32_SL_ANY); \
+ if (__builtin_expect(ret, 0)) \
+ pl_sub((lock), PLOCK32_SL_1 | PLOCK32_RL_1); \
+ } \
+ !ret; /* return value */ \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_try_s__(char *,int); \
+ __unsupported_argument_size_for_pl_try_s__(__FILE__,__LINE__); \
+ 0; \
+ }) \
+)
+
+/* request a seek access (S) and wait for it */
+#define pl_take_s(lock) \
+ do { \
+ while (__builtin_expect(pl_try_s(lock), 0) == 0) \
+ pl_cpu_relax(); \
+ } while (0)
+
+/* release the seek access (S) lock */
+#define pl_drop_s(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_SL_1 + PLOCK64_RL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_SL_1 + PLOCK32_RL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_drop_s__(char *,int); \
+ __unsupported_argument_size_for_pl_drop_s__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* drop the S lock and go back to the R lock */
+#define pl_stor(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_SL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_SL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_stor__(char *,int); \
+ __unsupported_argument_size_for_pl_stor__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* take the W lock under the S lock */
+#define pl_stow(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_xadd((lock), PLOCK64_WL_1); \
+ pl_barrier(); \
+ while ((ret & PLOCK64_RL_ANY) != PLOCK64_RL_1) \
+ ret = pl_deref_long(lock); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_xadd((lock), PLOCK32_WL_1); \
+ pl_barrier(); \
+ while ((ret & PLOCK32_RL_ANY) != PLOCK32_RL_1) \
+ ret = pl_deref_int(lock); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_stow__(char *,int); \
+ __unsupported_argument_size_for_pl_stow__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* drop the W lock and go back to the S lock */
+#define pl_wtos(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_WL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_WL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_wtos__(char *,int); \
+ __unsupported_argument_size_for_pl_wtos__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* drop the W lock and go back to the R lock */
+#define pl_wtor(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_WL_1 | PLOCK64_SL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_WL_1 | PLOCK32_SL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_wtor__(char *,int); \
+ __unsupported_argument_size_for_pl_wtor__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* request a write access (W), return non-zero on success, otherwise 0.
+ *
+ * Below there is something important : by taking both W and S, we will cause
+ * an overflow of W at 4/5 of the maximum value that can be stored into W due
+ * to the fact that S is 2 bits, so we're effectively adding 5 to the word
+ * composed by W:S. But for all words multiple of 4 bits, the maximum value is
+ * multiple of 15 thus of 5. So the largest value we can store with all bits
+ * set to one will be met by adding 5, and then adding 5 again will place value
+ * 1 in W and value 0 in S, so we never leave W with 0. Also, even upon such an
+ * overflow, there's no risk to confuse it with an atomic lock because R is not
+ * null since it will not have overflown. For 32-bit locks, this situation
+ * happens when exactly 13108 threads try to grab the lock at once, W=1, S=0
+ * and R=13108. For 64-bit locks, it happens at 858993460 concurrent writers
+ * where W=1, S=0 and R=858993460.
+ */
+#define pl_try_w(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_deref_long(lock); \
+ pl_barrier(); \
+ if (!__builtin_expect(ret & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
+ ret = pl_xadd((lock), PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
+ if (__builtin_expect(ret & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
+ /* a writer, seeker or atomic is present, let's leave */ \
+ pl_sub((lock), PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
+ ret &= (PLOCK64_WL_ANY | PLOCK64_SL_ANY); /* return value */ \
+ } else { \
+ /* wait for all other readers to leave */ \
+ while (ret) \
+ ret = pl_deref_long(lock) - \
+ (PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
+ ret = 0; \
+ } \
+ } \
+ !ret; /* return value */ \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_deref_int(lock); \
+ pl_barrier(); \
+ if (!__builtin_expect(ret & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
+ ret = pl_xadd((lock), PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
+ if (__builtin_expect(ret & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
+ /* a writer, seeker or atomic is present, let's leave */ \
+ pl_sub((lock), PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
+ ret &= (PLOCK32_WL_ANY | PLOCK32_SL_ANY); /* return value */ \
+ } else { \
+ /* wait for all other readers to leave */ \
+ while (ret) \
+ ret = pl_deref_int(lock) - \
+ (PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
+ ret = 0; \
+ } \
+ } \
+ !ret; /* return value */ \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_try_w__(char *,int); \
+ __unsupported_argument_size_for_pl_try_w__(__FILE__,__LINE__); \
+ 0; \
+ }) \
+)
+
+/* request a seek access (W) and wait for it */
+#define pl_take_w(lock) \
+ do { \
+ while (__builtin_expect(pl_try_w(lock), 0) == 0) \
+ pl_cpu_relax(); \
+ } while (0)
+
+/* drop the write (W) lock entirely */
+#define pl_drop_w(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_WL_1 | PLOCK64_SL_1 | PLOCK64_RL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_WL_1 | PLOCK32_SL_1 | PLOCK32_RL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_drop_w__(char *,int); \
+ __unsupported_argument_size_for_pl_drop_w__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* Try to upgrade from R to S, return non-zero on success, otherwise 0.
+ * This lock will fail if S or W are already held. In case of failure to grab
+ * the lock, it MUST NOT be retried without first dropping R, or it may never
+ * complete due to S waiting for R to leave before upgrading to W.
+ */
+#define pl_try_rtos(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_deref_long(lock); \
+ pl_barrier(); \
+ if (!__builtin_expect(ret & (PLOCK64_WL_ANY | PLOCK64_SL_ANY), 0)) { \
+ ret = pl_xadd((lock), PLOCK64_SL_1) & \
+ (PLOCK64_WL_ANY | PLOCK64_SL_ANY); \
+ if (__builtin_expect(ret, 0)) \
+ pl_sub((lock), PLOCK64_SL_1); \
+ } \
+ !ret; /* return value */ \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_deref_int(lock); \
+ pl_barrier(); \
+ if (!__builtin_expect(ret & (PLOCK32_WL_ANY | PLOCK32_SL_ANY), 0)) { \
+ ret = pl_xadd((lock), PLOCK32_SL_1) & \
+ (PLOCK32_WL_ANY | PLOCK32_SL_ANY); \
+ if (__builtin_expect(ret, 0)) \
+ pl_sub((lock), PLOCK32_SL_1); \
+ } \
+ !ret; /* return value */ \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_try_rtos__(char *,int); \
+ __unsupported_argument_size_for_pl_try_rtos__(__FILE__,__LINE__); \
+ 0; \
+ }) \
+)
+
+
+/* request atomic write access (A), return non-zero on success, otherwise 0.
+ * It's a bit tricky as we only use the W bits for this and want to distinguish
+ * between other atomic users and regular lock users. We have to give up if an
+ * S lock appears. It's possible that such a lock stays hidden in the W bits
+ * after an overflow, but in this case R is still held, ensuring we stay in the
+ * loop until we discover the conflict. The lock only return successfully if all
+ * readers are gone (or converted to A).
+ */
+#define pl_try_a(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_deref_long(lock) & PLOCK64_SL_ANY; \
+ pl_barrier(); \
+ if (!__builtin_expect(ret, 0)) { \
+ ret = pl_xadd((lock), PLOCK64_WL_1); \
+ while (1) { \
+ if (__builtin_expect(ret & PLOCK64_SL_ANY, 0)) { \
+ pl_sub((lock), PLOCK64_WL_1); \
+ break; /* return !ret */ \
+ } \
+ ret &= PLOCK64_RL_ANY; \
+ if (!__builtin_expect(ret, 0)) \
+ break; /* return !ret */ \
+ ret = pl_deref_long(lock); \
+ } \
+ } \
+ !ret; /* return value */ \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_deref_int(lock) & PLOCK32_SL_ANY; \
+ pl_barrier(); \
+ if (!__builtin_expect(ret, 0)) { \
+ ret = pl_xadd((lock), PLOCK32_WL_1); \
+ while (1) { \
+ if (__builtin_expect(ret & PLOCK32_SL_ANY, 0)) { \
+ pl_sub((lock), PLOCK32_WL_1); \
+ break; /* return !ret */ \
+ } \
+ ret &= PLOCK32_RL_ANY; \
+ if (!__builtin_expect(ret, 0)) \
+ break; /* return !ret */ \
+ ret = pl_deref_int(lock); \
+ } \
+ } \
+ !ret; /* return value */ \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_try_a__(char *,int); \
+ __unsupported_argument_size_for_pl_try_a__(__FILE__,__LINE__); \
+ 0; \
+ }) \
+)
+
+/* request atomic write access (A) and wait for it */
+#define pl_take_a(lock) \
+ do { \
+ while (__builtin_expect(pl_try_a(lock), 1) == 0) \
+ pl_cpu_relax(); \
+ } while (0)
+
+/* release atomic write access (A) lock */
+#define pl_drop_a(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ pl_sub(lock, PLOCK64_WL_1); \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ pl_sub(lock, PLOCK32_WL_1); \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_drop_a__(char *,int); \
+ __unsupported_argument_size_for_pl_drop_a__(__FILE__,__LINE__); \
+ }) \
+)
+
+/* Try to upgrade from R to A, return non-zero on success, otherwise 0.
+ * This lock will fail if S is held or appears while waiting (typically due to
+ * a previous grab that was disguised as a W due to an overflow). In case of
+ * failure to grab the lock, it MUST NOT be retried without first dropping R,
+ * or it may never complete due to S waiting for R to leave before upgrading
+ * to W. The lock succeeds once there's no more R (ie all of them have either
+ * completed or were turned to A).
+ */
+#define pl_try_rtoa(lock) ( \
+ (sizeof(long) == 8 && sizeof(*(lock)) == 8) ? ({ \
+ unsigned long ret = pl_deref_long(lock) & PLOCK64_SL_ANY; \
+ pl_barrier(); \
+ if (!__builtin_expect(ret, 0)) { \
+ ret = pl_xadd((lock), PLOCK64_WL_1 - PLOCK64_RL_1); \
+ while (1) { \
+ if (__builtin_expect(ret & PLOCK64_SL_ANY, 0)) { \
+ pl_sub((lock), PLOCK64_WL_1 - PLOCK64_RL_1); \
+ break; /* return !ret */ \
+ } \
+ ret &= PLOCK64_RL_ANY; \
+ if (!__builtin_expect(ret, 0)) \
+ break; /* return !ret */ \
+ ret = pl_deref_long(lock); \
+ } \
+ } \
+ !ret; /* return value */ \
+ }) : (sizeof(*(lock)) == 4) ? ({ \
+ unsigned int ret = pl_deref_int(lock) & PLOCK32_SL_ANY; \
+ pl_barrier(); \
+ if (!__builtin_expect(ret, 0)) { \
+ ret = pl_xadd((lock), PLOCK32_WL_1 - PLOCK32_RL_1); \
+ while (1) { \
+ if (__builtin_expect(ret & PLOCK32_SL_ANY, 0)) { \
+ pl_sub((lock), PLOCK32_WL_1 - PLOCK32_RL_1); \
+ break; /* return !ret */ \
+ } \
+ ret &= PLOCK32_RL_ANY; \
+ if (!__builtin_expect(ret, 0)) \
+ break; /* return !ret */ \
+ ret = pl_deref_int(lock); \
+ } \
+ } \
+ !ret; /* return value */ \
+ }) : ({ \
+ void __unsupported_argument_size_for_pl_try_rtoa__(char *,int); \
+ __unsupported_argument_size_for_pl_try_rtoa__(__FILE__,__LINE__); \
+ 0; \
+ }) \
+)