Changeset: 819615f16909 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=819615f16909
Modified Files:
gdk/gdk_atomic.h
Branch: default
Log Message:
Introduce ATOMIC_CAS (compare and set) macro/function.
diffs (98 lines):
diff --git a/gdk/gdk_atomic.h b/gdk/gdk_atomic.h
--- a/gdk/gdk_atomic.h
+++ b/gdk/gdk_atomic.h
@@ -17,6 +17,7 @@
* ATOMIC_GET -- return the value of a variable;
* ATOMIC_SET -- set the value of a variable;
* ATOMIC_XCG -- set the value of a variable, return original value;
+ * ATOMIC_CAS -- compare-and-set (see below)
* ATOMIC_ADD -- add a value to a variable, return original value;
* ATOMIC_SUB -- subtract a value from a variable, return original value;
* ATOMIC_INC -- increment a variable's value, return new value;
@@ -24,6 +25,12 @@
* These interfaces work on variables of type ATOMIC_TYPE
* (int or int64_t depending on architecture).
*
+ * The compare-and-set operation is based on the C11 standard: if the
+ * atomic variable equals the expected value, the atomic variable is
+ * replaced by the desired value and true is returned. Otherwise, the
+ * expected value is replaced by the current value of the atomic
+ * variable and false is returned.
+ *
* Some of these are also available for pointers:
* ATOMIC_PTR_INIT
* ATOMIC_GET_PTR
@@ -79,6 +86,7 @@ typedef unsigned long long ATOMIC_BASE_T
#define ATOMIC_GET(var) atomic_load(var)
#define ATOMIC_SET(var, val) atomic_store(var, (ATOMIC_BASE_TYPE) (val))
#define ATOMIC_XCG(var, val) atomic_exchange(var, (ATOMIC_BASE_TYPE) (val))
+#define ATOMIC_CAS(var, exp, des) atomic_compare_exchange_strong(var,
exp, (ATOMIC_BASE_TYPE) (des))
#define ATOMIC_ADD(var, val) atomic_fetch_add(var, (ATOMIC_BASE_TYPE) (val))
#define ATOMIC_SUB(var, val) atomic_fetch_sub(var, (ATOMIC_BASE_TYPE) (val))
#define ATOMIC_INC(var) (atomic_fetch_add(var, 1) + 1)
@@ -129,6 +137,16 @@ typedef int64_t ATOMIC_BASE_TYPE;
#endif
#define ATOMIC_SET(var, val) _InterlockedExchange64(var, (ATOMIC_BASE_TYPE)
(val))
#define ATOMIC_XCG(var, val) _InterlockedExchange64(var, (ATOMIC_BASE_TYPE)
(val))
+static inline bool
+ATOMIC_CAS(ATOMIC_TYPE *var, ATOMIC_BASE_TYPE *exp, ATOMIC_BASE_TYPE des)
+{
+ ATOMIC_BASE_TYPE old;
+ old = _InterlockedCompareExchange64(var, des, *exp);
+ if (old == *exp)
+ return true;
+ *exp = old;
+ return false;
+}
#define ATOMIC_ADD(var, val) _InterlockedExchangeAdd64(var,
(ATOMIC_BASE_TYPE) (val))
#define ATOMIC_SUB(var, val) _InterlockedExchangeAdd64(var,
-(ATOMIC_BASE_TYPE) (val))
#define ATOMIC_INC(var) _InterlockedIncrement64(var)
@@ -155,6 +173,16 @@ typedef int ATOMIC_BASE_TYPE;
#endif
#define ATOMIC_SET(var, val) _InterlockedExchange(var, (ATOMIC_BASE_TYPE)
(val))
#define ATOMIC_XCG(var, val) _InterlockedExchange(var, (ATOMIC_BASE_TYPE)
(val))
+static inline bool
+ATOMIC_CAS(ATOMIC_TYPE *var, ATOMIC_BASE_TYPE *exp, ATOMIC_BASE_TYPE des)
+{
+ ATOMIC_BASE_TYPE old;
+ old = _InterlockedCompareExchange(var, des, *exp);
+ if (old == *exp)
+ return true;
+ *exp = old;
+ return false;
+}
#define ATOMIC_ADD(var, val) _InterlockedExchangeAdd(var, (ATOMIC_BASE_TYPE)
(val))
#define ATOMIC_SUB(var, val) _InterlockedExchangeAdd(var,
-(ATOMIC_BASE_TYPE) (val))
#define ATOMIC_INC(var) _InterlockedIncrement(var)
@@ -195,6 +223,7 @@ typedef int ATOMIC_TYPE;
#define ATOMIC_GET(var) __atomic_load_n(var, __ATOMIC_SEQ_CST)
#define ATOMIC_SET(var, val) __atomic_store_n(var, (ATOMIC_TYPE) (val),
__ATOMIC_SEQ_CST)
#define ATOMIC_XCG(var, val) __atomic_exchange_n(var, (ATOMIC_TYPE) (val),
__ATOMIC_SEQ_CST
+#define ATOMIC_CAS(var, exp, des) __atomic_compare_exchange_n(var, exp,
(ATOMIC_TYPE) (des), false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)
#define ATOMIC_ADD(var, val) __atomic_fetch_add(var, (ATOMIC_TYPE) (val),
__ATOMIC_SEQ_CST)
#define ATOMIC_SUB(var, val) __atomic_fetch_sub(var, (ATOMIC_TYPE) (val),
__ATOMIC_SEQ_CST)
#define ATOMIC_INC(var) __atomic_add_fetch(var, 1,
__ATOMIC_SEQ_CST)
@@ -260,6 +289,23 @@ ATOMIC_XCG(ATOMIC_TYPE *var, ATOMIC_BASE
}
#define ATOMIC_XCG(var, val) ATOMIC_XCG(var, (ATOMIC_BASE_TYPE) (val))
+static inline bool
+ATOMIC_CAS(ATOMIC_TYPE *var, ATOMIC_BASE_TYPE *exp, ATOMIC_BASE_TYPE des)
+{
+ bool ret;
+ pthread_mutex_lock(&var->lck);
+ if (var->val == *exp) {
+ var->val = des;
+ ret = true;
+ } else {
+ *exp = var->val;
+ ret = false;
+ }
+ pthread_mutex_unlock(&var->lck);
+ return ret;
+}
+#define ATOMIC_CAS(var, exp, des) ATOMIC_CAS(var, exp, (ATOMIC_BASE_TYPE)
(des))
+
static inline ATOMIC_BASE_TYPE
ATOMIC_ADD(ATOMIC_TYPE *var, ATOMIC_BASE_TYPE val)
{
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