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smp: add user pthread helpers that are NOP for LWS_SMP_MAX == 1

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This commit is contained in:
Andy Green 2018-03-02 14:24:25 +08:00
parent 3de2e9aa8a
commit 0d8b11d250
2 changed files with 73 additions and 5 deletions
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35
READMEs/README.coding.md
View file

@ -899,18 +899,43 @@ You can set fd_limit_per_thread to a nonzero number to control this manually, eg
the overall supported fd limit is less than the process allowance.
You can control the context basic data allocation for multithreading from Cmake
using -DLWS_MAX_SMP=, if not given it's set to 32. The serv_buf allocation
using -DLWS_MAX_SMP=, if not given it's set to 1. The serv_buf allocation
for the threads (currently 4096) is made at runtime only for active threads.
Because lws will limit the requested number of actual threads supported
according to LWS_MAX_SMP, there is an api lws_get_count_threads(context) to
discover how many threads were actually allowed when the context was created.
It's required to implement locking in the user code in the same way that
libwebsockets-test-server-pthread does it, for the FD locking callbacks.
See the test-server-pthreads.c sample for how to use.
There is no knowledge or dependency in lws itself about pthreads. How the
locking is implemented is entirely up to the user code.
@section smplocking SMP Locking Helpers
Lws provide a set of pthread mutex helpers that reduce to no code or
variable footprint in the case that LWS_MAX_SMP == 1.
Define your user mutex like this
```
lws_pthread_mutex(name);
```
If LWS_MAX_SMP > 1, this produces `pthread_mutex_t name;`. In the case
LWS_MAX_SMP == 1, it produces nothing.
Likewise these helpers for init, destroy, lock and unlock
```
void lws_pthread_mutex_init(pthread_mutex_t *lock)
void lws_pthread_mutex_destroy(pthread_mutex_t *lock)
void lws_pthread_mutex_lock(pthread_mutex_t *lock)
void lws_pthread_mutex_unlock(pthread_mutex_t *lock)
```
resolve to nothing if LWS_MAX_SMP == 1, otherwise produce the equivalent
pthread api.
pthreads is required in lws only if LWS_MAX_SMP > 1.
@section libevuv libev / libuv / libevent support

43
lib/libwebsockets.h
View file

@ -215,6 +215,49 @@ typedef unsigned long long lws_intptr_t;
#endif /* not USE_WOLFSSL */
#endif
/*
* Helpers for pthread mutex in user code... if lws is built for
* multiple service threads, these resolve to pthread mutex
* operations. In the case LWS_MAX_SMP is 1 (the default), they
* are all NOPs and no pthread type or api is referenced.
*/
#if LWS_MAX_SMP > 1
#define lws_pthread_mutex(name) pthread_mutex_t name
static LWS_INLINE void
lws_pthread_mutex_init(pthread_mutex_t *lock)
{
pthread_mutex_init(lock, NULL);
}
static LWS_INLINE void
lws_pthread_mutex_destroy(pthread_mutex_t *lock)
{
pthread_mutex_destroy(lock);
}
static LWS_INLINE void
lws_pthread_mutex_lock(pthread_mutex_t *lock)
{
pthread_mutex_lock(lock);
}
static LWS_INLINE void
lws_pthread_mutex_unlock(pthread_mutex_t *lock)
{
pthread_mutex_unlock(lock);
}
#else
#define lws_pthread_mutex(name)
#define lws_pthread_mutex_init(_a)
#define lws_pthread_mutex_destroy(_a)
#define lws_pthread_mutex_lock(_a)
#define lws_pthread_mutex_unlock(_a)
#endif
#define CONTEXT_PORT_NO_LISTEN -1
#define CONTEXT_PORT_NO_LISTEN_SERVER -2