[ovs-dev] [thread 02/15] ovs-thread: Add support for globally visible per-thread data.
Ethan Jackson
ethan at nicira.com
Thu Aug 8 19:58:21 UTC 2013
From: Ben Pfaff <blp at nicira.com>
DEFINE_PER_THREAD_DATA always declared its data item as "static", meaning
that it was only directly visible within a single translation unit.
This commit adds additional forms of per-thread data that allow the data
to be accessible from multiple translation units.
Signed-off-by: Ben Pfaff <blp at nicira.com>
---
lib/ovs-thread.h | 94 ++++++++++++++++++++++++++++++++++++++++++++----------
lib/random.c | 2 +-
lib/timeval.c | 2 +-
lib/util.c | 4 ++-
lib/vlog.c | 2 +-
5 files changed, 84 insertions(+), 20 deletions(-)
diff --git a/lib/ovs-thread.h b/lib/ovs-thread.h
index 0d54a43..abe479a 100644
--- a/lib/ovs-thread.h
+++ b/lib/ovs-thread.h
@@ -193,7 +193,15 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *);
* cross-thread access? yes no yes
*/
-/* DEFINE_PER_THREAD_DATA(TYPE, NAME, INITIALIZER).
+/* For static data, use this macro in a source file:
+ *
+ * DEFINE_STATIC_PER_THREAD_DATA(TYPE, NAME, INITIALIZER).
+ *
+ * For global data, "declare" the data in the header and "define" it in
+ * the source file, with:
+ *
+ * DECLARE_EXTERN_PER_THREAD_DATA(TYPE, NAME).
+ * DEFINE_EXTERN_PER_THREAD_DATA(NAME, INITIALIZER).
*
* One should prefer to use POSIX per-thread data, via pthread_key_t, when its
* performance is acceptable, because of its portability (see the table above).
@@ -231,23 +239,40 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *);
#error
#endif
-#define DEFINE_PER_THREAD_DATA(TYPE, NAME, ...) \
- typedef TYPE NAME##_type; \
- static thread_local NAME##_type NAME##_var = __VA_ARGS__; \
- \
- static NAME##_type * \
- NAME##_get_unsafe(void) \
- { \
- return &NAME##_var; \
- } \
- \
- static NAME##_type * \
- NAME##_get(void) \
- { \
- return NAME##_get_unsafe(); \
+#define DEFINE_STATIC_PER_THREAD_DATA(TYPE, NAME, ...) \
+ typedef TYPE NAME##_type; \
+ \
+ static NAME##_type * \
+ NAME##_get_unsafe(void) \
+ { \
+ static thread_local NAME##_type var = __VA_ARGS__; \
+ return &var; \
+ } \
+ \
+ static NAME##_type * \
+ NAME##_get(void) \
+ { \
+ return NAME##_get_unsafe(); \
}
+#define DECLARE_EXTERN_PER_THREAD_DATA(TYPE, NAME) \
+ typedef TYPE NAME##_type; \
+ extern thread_local NAME##_type NAME##_var; \
+ \
+ static inline NAME##_type * \
+ NAME##_get_unsafe(void) \
+ { \
+ return &NAME##_var; \
+ } \
+ \
+ static inline NAME##_type * \
+ NAME##_get(void) \
+ { \
+ return NAME##_get_unsafe(); \
+ }
+#define DEFINE_EXTERN_PER_THREAD_DATA(NAME, ...) \
+ thread_local NAME##_type NAME##_var = __VA_ARGS__;
#else /* no C implementation support for thread-local storage */
-#define DEFINE_PER_THREAD_DATA(TYPE, NAME, ...) \
+#define DEFINE_STATIC_PER_THREAD_DATA(TYPE, NAME, ...) \
typedef TYPE NAME##_type; \
static pthread_key_t NAME##_key; \
\
@@ -282,6 +307,43 @@ void xpthread_create(pthread_t *, pthread_attr_t *, void *(*)(void *), void *);
} \
return value; \
}
+#define DECLARE_EXTERN_PER_THREAD_DATA(TYPE, NAME) \
+ typedef TYPE NAME##_type; \
+ static pthread_key_t NAME##_key; \
+ \
+ static inline NAME##_type * \
+ NAME##_get_unsafe(void) \
+ { \
+ return pthread_getspecific(NAME##_key); \
+ } \
+ \
+ NAME##_type *NAME##_get(void);
+#define DEFINE_EXTERN_PER_THREAD_DATA(NAME, ...) \
+ static void \
+ NAME##_once_init(void) \
+ { \
+ if (pthread_key_create(&NAME##_key, free)) { \
+ abort(); \
+ } \
+ } \
+ \
+ NAME##_type * \
+ NAME##_get(void) \
+ { \
+ static pthread_once_t once = PTHREAD_ONCE_INIT; \
+ NAME##_type *value; \
+ \
+ pthread_once(&once, NAME##_once_init); \
+ value = NAME##_get_unsafe(); \
+ if (!value) { \
+ static const NAME##_type initial_value = __VA_ARGS__; \
+ \
+ value = xmalloc(sizeof *value); \
+ *value = initial_value; \
+ xpthread_setspecific(NAME##_key, value); \
+ } \
+ return value; \
+ }
#endif
/* DEFINE_PER_THREAD_MALLOCED_DATA(TYPE, NAME).
diff --git a/lib/random.c b/lib/random.c
index da29fd0..d6f7d9d 100644
--- a/lib/random.c
+++ b/lib/random.c
@@ -39,7 +39,7 @@
* cryptographic-quality randomness. */
/* Current random state. */
-DEFINE_PER_THREAD_DATA(uint32_t, seed, 0);
+DEFINE_STATIC_PER_THREAD_DATA(uint32_t, seed, 0);
static uint32_t random_next(void);
diff --git a/lib/timeval.c b/lib/timeval.c
index 05da99e..faf8e7b 100644
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -65,7 +65,7 @@ static long long int deadline = LLONG_MAX;
/* Monotonic time, in milliseconds, at which the last call to time_poll() woke
* up. */
-DEFINE_PER_THREAD_DATA(long long int, last_wakeup, 0);
+DEFINE_STATIC_PER_THREAD_DATA(long long int, last_wakeup, 0);
static void set_up_timer(void);
static void set_up_signal(int flags);
diff --git a/lib/util.c b/lib/util.c
index 1751c6f..76c33cd 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -46,7 +46,9 @@ DEFINE_PER_THREAD_MALLOCED_DATA(char *, subprogram_name);
static char *program_version;
/* Buffer used by ovs_strerror(). */
-DEFINE_PER_THREAD_DATA(struct { char s[128]; }, strerror_buffer, { "" });
+DEFINE_STATIC_PER_THREAD_DATA(struct { char s[128]; },
+ strerror_buffer,
+ { "" });
void
ovs_assert_failure(const char *where, const char *function,
diff --git a/lib/vlog.c b/lib/vlog.c
index 26d0e6c..ac229b4 100644
--- a/lib/vlog.c
+++ b/lib/vlog.c
@@ -100,7 +100,7 @@ static struct facility facilities[VLF_N_FACILITIES] = {
};
/* Sequence number for the message currently being composed. */
-DEFINE_PER_THREAD_DATA(unsigned int, msg_num, 0);
+DEFINE_STATIC_PER_THREAD_DATA(unsigned int, msg_num, 0);
/* VLF_FILE configuration.
*
--
1.7.9.5
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