最新版（2013.01.17）x264的多线程代码研究（一）
先罗列出代码中与多线程有关的宏定义、结构体、变量、函数等，锁定为需要重点关注的对象，在接下来的研究中逐步深入探讨这些对象的含义和作用。
define X264_THREAD_MAX 128#define X264_LOOKAHEAD_THREAD_MAX 16#define X264_LOOKAHEAD_MAX 250// arbitrary, but low because SATD scores are 1/4 normal#define X264_LOOKAHEAD_QP (12+QP_BD_OFFSET)// number of pixels (per thread) in progress at any given time.// 16 for the macroblock in progress + 3 for deblocking + 3 for motion compensation filter + 2 for extra safety#define X264_THREAD_HEIGHT 24#define x264_pthread_t pthread_t#define x264_pthread_create pthread_create#define x264_pthread_join pthread_join#define x264_pthread_mutex_t pthread_mutex_t#define x264_pthread_mutex_init pthread_mutex_init#define x264_pthread_mutex_destroy pthread_mutex_destroy#define x264_pthread_mutex_lock pthread_mutex_lock#define x264_pthread_mutex_unlock pthread_mutex_unlock#define x264_pthread_cond_t pthread_cond_t#define x264_pthread_cond_init pthread_cond_init#define x264_pthread_cond_destroy pthread_cond_destroy#define x264_pthread_cond_broadcast pthread_cond_broadcast#define x264_pthread_cond_wait pthread_cond_wait#define x264_pthread_attr_t pthread_attr_t#define x264_pthread_attr_init pthread_attr_init#define x264_pthread_attr_destroy pthread_attr_destroy#define x264_pthread_num_processors_np pthread_num_processors_np#define X264_PTHREAD_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZERtypedef struct x264_lookahead_t{ volatile uint8_t b_exit_thread; uint8_t b_thread_active; uint8_t b_analyse_keyframe; int i_last_keyframe; int i_slicetype_length; x264_frame_t *last_nonb; x264_pthread_t thread_handle; x264_sync_frame_list_t ifbuf; x264_sync_frame_list_t next; x264_sync_frame_list_t ofbuf;} x264_lookahead_t;/* synchronized frame list */typedef struct{ x264_frame_t **list; int i_max_size; int i_size; x264_pthread_mutex_t mutex; x264_pthread_cond_t cv_fill; /* event signaling that the list became fuller */ x264_pthread_cond_t cv_empty; /* event signaling that the list became emptier */} x264_sync_frame_list_t;typedef struct x264_frame //!< 为节省篇幅，仅附上与线程有关的成员变量{ /* threading */ int i_lines_completed; /* in pixels */ int i_lines_weighted; /* FIXME: this only supports weighting of one reference frame */ int i_reference_count; /* number of threads using this frame (not necessarily the number of pointers) */ x264_pthread_mutex_t mutex; x264_pthread_cond_t cv;} x264_frame_t;/* threading */void x264_frame_cond_broadcast( x264_frame_t *frame, int i_lines_completed ){ x264_pthread_mutex_lock( &frame->mutex ); frame->i_lines_completed = i_lines_completed; x264_pthread_cond_broadcast( &frame->cv ); x264_pthread_mutex_unlock( &frame->mutex );}void x264_frame_cond_wait( x264_frame_t *frame, int i_lines_completed ){ x264_pthread_mutex_lock( &frame->mutex ); while( frame->i_lines_completed < i_lines_completed ) x264_pthread_cond_wait( &frame->cv, &frame->mutex ); x264_pthread_mutex_unlock( &frame->mutex );}void x264_threadslice_cond_broadcast( x264_t *h, int pass ){ x264_pthread_mutex_lock( &h->mutex ); h->i_threadslice_pass = pass; if( pass > 0 ) x264_pthread_cond_broadcast( &h->cv ); x264_pthread_mutex_unlock( &h->mutex );}void x264_threadslice_cond_wait( x264_t *h, int pass ){ x264_pthread_mutex_lock( &h->mutex ); while( h->i_threadslice_pass < pass ) x264_pthread_cond_wait( &h->cv, &h->mutex ); x264_pthread_mutex_unlock( &h->mutex );}int x264_sync_frame_list_init( x264_sync_frame_list_t *slist, int max_size ){ if( max_size < 0 ) return -1; slist->i_max_size = max_size; slist->i_size = 0; CHECKED_MALLOCZERO( slist->list, (max_size+1) * sizeof(x264_frame_t*) ); if( x264_pthread_mutex_init( &slist->mutex, NULL ) || x264_pthread_cond_init( &slist->cv_fill, NULL ) || x264_pthread_cond_init( &slist->cv_empty, NULL ) ) return -1; return 0;fail: return -1;}void x264_sync_frame_list_delete( x264_sync_frame_list_t *slist ){ x264_pthread_mutex_destroy( &slist->mutex ); x264_pthread_cond_destroy( &slist->cv_fill ); x264_pthread_cond_destroy( &slist->cv_empty ); x264_frame_delete_list( slist->list );}void x264_sync_frame_list_push( x264_sync_frame_list_t *slist, x264_frame_t *frame ){ x264_pthread_mutex_lock( &slist->mutex ); while( slist->i_size == slist->i_max_size ) x264_pthread_cond_wait( &slist->cv_empty, &slist->mutex ); slist->list[ slist->i_size++ ] = frame; x264_pthread_mutex_unlock( &slist->mutex ); x264_pthread_cond_broadcast( &slist->cv_fill );}x264_frame_t *x264_sync_frame_list_pop( x264_sync_frame_list_t *slist ){ x264_frame_t *frame; x264_pthread_mutex_lock( &slist->mutex ); while( !slist->i_size ) x264_pthread_cond_wait( &slist->cv_fill, &slist->mutex ); frame = slist->list[ --slist->i_size ]; slist->list[ slist->i_size ] = NULL; x264_pthread_cond_broadcast( &slist->cv_empty ); x264_pthread_mutex_unlock( &slist->mutex ); return frame;} typedef struct x264_param_t //!< 为节省篇幅，仅附上与线程有关的成员变量{ /* CPU flags */ unsigned int cpu; int i_threads; /* encode multiple frames in parallel */ int i_lookahead_threads; /* multiple threads for lookahead analysis */ int b_sliced_threads; /* Whether to use slice-based threading. */ int b_deterministic; /* whether to allow non-deterministic optimizations when threaded */ int b_cpu_independent; /* force canonical behavior rather than cpu-dependent optimal algorithms */ int i_sync_lookahead; /* threaded lookahead buffer */}x264_param_t; struct x264_t //!< 为节省篇幅，仅附上与线程有关的成员变量{ /* encoder parameters */ x264_param_t param; x264_t *thread[X264_THREAD_MAX+1]; x264_t *lookahead_thread[X264_LOOKAHEAD_THREAD_MAX]; int b_thread_active; int i_thread_phase; /* which thread to use for the next frame */ int i_thread_idx; /* which thread this is */ int i_threadslice_start; /* first row in this thread slice */ int i_threadslice_end; /* row after the end of this thread slice */ int i_threadslice_pass; /* which pass of encoding we are on */ x264_threadpool_t *threadpool; x264_threadpool_t *lookaheadpool; x264_pthread_mutex_t mutex; x264_pthread_cond_t cv;}