diff options
Diffstat (limited to 'lf_ring_buffer.c')
| -rw-r--r-- | lf_ring_buffer.c | 48 |
1 files changed, 34 insertions, 14 deletions
diff --git a/lf_ring_buffer.c b/lf_ring_buffer.c index ec071ec..70074bc 100644 --- a/lf_ring_buffer.c +++ b/lf_ring_buffer.c @@ -31,16 +31,28 @@ #include <string.h> #include <time.h> -//#define DEBUG_LFR_RING 1 +//#define DEBUG_LFRB_KO 1 +//#define DEBUG_LFRB_CAS 1 +//#define DEBUG_LFRB 1 -#ifdef DEBUG_LFR_RING +#ifdef DEBUG_LFRB #include <stdio.h> - #define _LOG_( ... ) fprintf(stdout,__VA_ARGS__) + #define _LOG_KO_( ... ) fprintf(stdout,__VA_ARGS__) + #define _LOG_CAS_( ... ) fprintf(stdout,__VA_ARGS__) +#elif defined DEBUG_LFRB_CAS + #include <stdio.h> + #define _LOG_KO_( ... ) + #define _LOG_CAS_( ... ) fprintf(stdout,__VA_ARGS__) +#elif defined DEBUG_LFRB_KO + #include <stdio.h> + #define _LOG_KO_( ... ) fprintf(stdout,__VA_ARGS__) + #define _LOG_CAS_( ... ) #else - #define _LOG_( ... ) + #define _LOG_KO_( ... ) + #define _LOG_CAS_( ... ) #endif -#define BACKOFF_NANO_SLEEP 100 +#define BACKOFF_NANO_SLEEP 100000 /* initialize an empty lf_ring_buffer struct */ lf_ring_buffer_t* lf_ring_buffer_create( size_t n_buf ) { @@ -66,10 +78,14 @@ void lf_ring_buffer_destroy( lf_ring_buffer_t *r ) { free(r); } +/* return 1 if is empty */ +int lf_ring_buffer_empty( lf_ring_buffer_t *r ) { return r->read_from==-1; } + /* write data into the ring buffer */ int lf_ring_buffer_write( lf_ring_buffer_t *r, void *data, int flags ) { int idx, next; struct timespec backoff; + int backoff_time = BACKOFF_NANO_SLEEP; /* reserve a buffer */ for(;;){ idx = r->write_to; @@ -84,7 +100,7 @@ int lf_ring_buffer_write( lf_ring_buffer_t *r, void *data, int flags ) { * - a writter has reserved this buffer => write_to has moved => CAS fails * - a reader has consumed a buffer => read_from has moved => we've got more space */ - _LOG_( "write: CAS %d %d %d\n", r->write_to, idx, next ); + _LOG_CAS_( "write: CAS %d %d %d\n", r->write_to, idx, next ); if( CompareAndSwapInt( &r->write_to, idx, next ) ) { /* !!!!!!!!!!!!!! WARNING !!!!!!!!!!!!!!!!! * - if the ring is empty before this write operation (r->read_from==-1 or latest idx) @@ -98,19 +114,20 @@ int lf_ring_buffer_write( lf_ring_buffer_t *r, void *data, int flags ) { break; } } else { - _LOG_("write: ring full %d %d\n",r->read_from,idx); + _LOG_KO_("write: ring full %d %d\n",r->read_from,idx); if(IS_NOT_BLOCKING(flags)) return -1; backoff.tv_sec = 0; - backoff.tv_nsec = BACKOFF_NANO_SLEEP; + backoff.tv_nsec = backoff_time; nanosleep(&backoff,NULL); } } else { - _LOG_("write: buffer not available\n"); + _LOG_KO_("write: buffer not available\n"); if(IS_NOT_BLOCKING(flags)) return -1; backoff.tv_sec = 0; - backoff.tv_nsec = BACKOFF_NANO_SLEEP; + backoff.tv_nsec = backoff_time; nanosleep(&backoff,NULL); } + backoff_time += BACKOFF_NANO_SLEEP; } /* fill this buffer and mark it as filled */ memcpy( LFRB_DATA_PTR(r->buffer[idx]), data, LFRB_DATA_SIZE ); @@ -122,6 +139,7 @@ int lf_ring_buffer_write( lf_ring_buffer_t *r, void *data, int flags ) { int lf_ring_buffer_read( lf_ring_buffer_t *r, void *data, int flags ) { int idx, next; struct timespec backoff; + int backoff_time = BACKOFF_NANO_SLEEP; for(;;) { idx = r->read_from; if( !(LFRB_IS_AVAILABLE( r->buffer[idx] )) && r->read_from!=-1 ) { @@ -129,21 +147,23 @@ int lf_ring_buffer_read( lf_ring_buffer_t *r, void *data, int flags ) { if (next==r->n_buf) next=0; /* will do bad things if data dst buffer is too small !! */ memcpy( data, LFRB_DATA_PTR(r->buffer[idx]), LFRB_DATA_SIZE ); - _LOG_( "read: CAS %d %d %d\n", r->read_from, idx, next ); + _LOG_CAS_( "read: CAS %d %d %d\n", r->read_from, idx, next ); if( CompareAndSwapInt( &r->read_from, idx, next ) ) { if(r->read_from==r->write_to) { /* the buffer is empty but writers will see it as full */ - _LOG_( "read: empty CAS %d %d %d\n", r->read_from, next, -1 ); + _LOG_CAS_( "read: empty CAS %d %d %d\n", r->read_from, next, -1 ); CompareAndSwapInt( &r->read_from, next, -1 ); } break; } } - _LOG_("read: ring empty\n"); + + _LOG_KO_("read: ring empty\n"); if(IS_NOT_BLOCKING(flags)) return -1; backoff.tv_sec = 0; - backoff.tv_nsec = BACKOFF_NANO_SLEEP; + backoff.tv_nsec = backoff_time; nanosleep(&backoff,NULL); + backoff_time += BACKOFF_NANO_SLEEP; } /* finish the read process */ LFRB_MARK_AS_READ( r->buffer[idx] ); |