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cothreads — userspace threads
#include <gst/gst.h> struct cothread_state; int (*cothread_func) (int argc, char **argv); struct cothread_context; #define COTHREAD_STARTED #define COTHREAD_DESTROYED cothread_context* cothread_context_init (void); void cothread_context_free (cothread_context *ctx); gpointer cothread_get_private (cothread_state *cothread); void cothread_set_private (cothread_state *cothread, gpointer data); cothread_state* cothread_create (cothread_context *ctx); void cothread_free (cothread_state *cothread); void cothread_setfunc (cothread_state *cothread, cothread_func func, int argc, char **argv); void cothread_stop (cothread_state *cothread); void cothread_switch (cothread_state *cothread); gpointer cothread_context_get_data (cothread_state *cothread, gchar *key); void cothread_context_set_data (cothread_state *cothread, gchar *key, gpointer data); void cothread_lock (cothread_state *cothread); gboolean cothread_trylock (cothread_state *cothread); void cothread_unlock (cothread_state *cothread); cothread_state* cothread_main (cothread_context *ctx); cothread_state* cothread_current_main (void); cothread_state* cothread_current (void);
Cothreads are a simple user-space method for switching between subtasks. They're based on setjmp()/longjmp() in their current form.
Cothreads are used for loop-based elements that pull data instead of being fed with data. Cothreads are usually used by a GstScheduler.
struct cothread_state {
cothread_context *ctx;
int cothreadnum;
gpointer priv;
cothread_func func;
int argc;
char **argv;
int flags;
void *sp;
jmp_buf jmp;
void *stack_base;
unsigned long stack_size;
int magic_number;
};
The cothread state structure
int (*cothread_func) (int argc,
char **argv);the function that will be called when the cothread starts. The function prototype is like a main() function, so you can do whatever you want with it.
| argc : | a main-like argument count |
| argv : | a main-like array of arguments |
| Returns : | a return code |
struct cothread_context {
GSList * cothreads; /* contains all threads but main */
cothread * main;
cothread * current;
GMutex * mutex;
GstThread * gst_thread; /* the GstThread we're running from */
};
The cothread context structure
cothread_context* cothread_context_init (void);
Create and initialize a new cothread context
| Returns : | the new cothread context |
void cothread_context_free (cothread_context *ctx);
Free the cothread context.
| ctx : | the cothread context to free |
gpointer cothread_get_private (cothread_state *cothread);
get the private data from the cothread
| cothread : | the cothread state |
| Returns : | the private data of the cothread |
void cothread_set_private (cothread_state *cothread, gpointer data);
set private data for the cothread.
| cothread : | the cothread state |
| data : | the data |
cothread_state* cothread_create (cothread_context *ctx);
Create a new cothread state in the given context
| ctx : | the cothread context |
| Returns : | the new cothread state or NULL on error |
void cothread_free (cothread_state *cothread);
Free the given cothread state
| cothread : | the cothread state |
void cothread_setfunc (cothread_state *cothread, cothread_func func, int argc, char **argv);
Set the cothread function
| cothread : | the cothread state |
| func : | the function to call |
| argc : | argument count for the cothread function |
| argv : | arguments for the cothread function |
void cothread_stop (cothread_state *cothread);
Stop the cothread and reset the stack and program counter.
| cothread : | the cothread to stop |
void cothread_switch (cothread_state *cothread);
Switches to the given cothread state
| cothread : | cothread state to switch to |
gpointer cothread_context_get_data (cothread_state *cothread, gchar *key);
get data from the cothread
| cothread : | the cothread state |
| key : | a key for the data |
| Returns : | the data associated with the key |
void cothread_context_set_data (cothread_state *cothread, gchar *key, gpointer data);
adds data to a cothread
| cothread : | the cothread state |
| key : | a key for the data |
| data : | the data |
void cothread_lock (cothread_state *cothread);
Locks the cothread state.
| cothread : | cothread state to lock |
gboolean cothread_trylock (cothread_state *cothread);
Try to lock the cothread state
| cothread : | cothread state to try to lock |
| Returns : | TRUE if the cothread could be locked. |
void cothread_unlock (cothread_state *cothread);
Unlock the cothread state.
| cothread : | cothread state to unlock |
cothread_state* cothread_main (cothread_context *ctx);
Gets the main thread.
| ctx : | cothread context to find main cothread of. |
| Returns : | the cothread_state of the main (0th) cothread. |
cothread_state* cothread_current_main (void);
Get the main thread in the current GThread.
| Returns : | the cothread_state of the main (0th) thread in the current GThread |
cothread_state* cothread_current (void);
Get the currenttly executing cothread
| Returns : | the cothread_state of the current cothread |
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