source: lib/ior-thread.c @ 15e9390

#include "wandio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <pthread.h>
#include <string.h>
#include <stdbool.h>

/* 1MB Buffer */
#define BUFFERSIZE (1024*1024)
#define BUFFERS 100

extern io_source_t thread_source;

struct buffer_t {
        char buffer[BUFFERSIZE];
        int len;
        enum { EMPTY = 0, FULL = 1 } state;
};

struct state_t {
        struct buffer_t buffer[BUFFERS];
        int in_buffer;
        int offset;
        pthread_t producer;
        pthread_cond_t space_avail;
        pthread_cond_t data_ready;
        pthread_mutex_t mutex;
        io_t *io;
        bool closing;
};

#define DATA(x) ((struct state_t *)((x)->data))
#define INBUFFER(x) (DATA(x)->buffer[DATA(x)->in_buffer])
#define min(a,b) ((a)<(b) ? (a) : (b))

static void *thread_producer(void* userdata)
{
        io_t *state = (io_t*) userdata;
        int buffer=0;
        bool running = true;

        pthread_mutex_lock(&DATA(state)->mutex);
        do {
                while (DATA(state)->buffer[buffer].state == FULL) {
                        if (DATA(state)->closing)
                                break;
                        pthread_cond_wait(&DATA(state)->space_avail, &DATA(state)->mutex);
                }

                if (DATA(state)->closing) {
                        break;
                }
                pthread_mutex_unlock(&DATA(state)->mutex);

                /* Fill the buffer */
                DATA(state)->buffer[buffer].len=wandio_read(
                                DATA(state)->io,
                                DATA(state)->buffer[buffer].buffer,
                                sizeof(DATA(state)->buffer[buffer].buffer));

                pthread_mutex_lock(&DATA(state)->mutex);

                DATA(state)->buffer[buffer].state = FULL;

                /* if we've not reached the end of the file keep going */
                running = (DATA(state)->buffer[buffer].len > 0 );

                pthread_cond_signal(&DATA(state)->data_ready);

                /* Flip buffers */
                buffer=(buffer+1) % BUFFERS;

        } while(running);


        wandio_destroy(DATA(state)->io);

        pthread_cond_signal(&DATA(state)->data_ready);
        pthread_mutex_unlock(&DATA(state)->mutex);

        return NULL;
}

io_t *thread_open(io_t *parent)
{
        io_t *state;

        if (!parent) {
                return NULL;
        }
        

        state = malloc(sizeof(io_t));
        state->data = calloc(1,sizeof(struct state_t));
        state->source = &thread_source;

        DATA(state)->in_buffer = 0;
        DATA(state)->offset = 0;
        pthread_mutex_init(&DATA(state)->mutex,NULL);
        pthread_cond_init(&DATA(state)->data_ready,NULL);
        pthread_cond_init(&DATA(state)->space_avail,NULL);

        DATA(state)->io = parent;
        DATA(state)->closing = false;

        pthread_create(&DATA(state)->producer,NULL,thread_producer,state);

        return state;
}

static off_t thread_read(io_t *state, void *buffer, off_t len)
{
        int slice;
        int copied=0;
        int newbuffer;

        while(len>0) {
                pthread_mutex_lock(&DATA(state)->mutex);
                while (INBUFFER(state).state == EMPTY) {
                        pthread_cond_wait(&DATA(state)->data_ready, &DATA(state)->mutex);

                }

                if (INBUFFER(state).len <1) {

                        if (copied<1)
                                copied = INBUFFER(state).len;

                        pthread_mutex_unlock(&DATA(state)->mutex);
                        return copied;
                }

                slice=min( INBUFFER(state).len-DATA(state)->offset,len);

                pthread_mutex_unlock(&DATA(state)->mutex);
                                
                memcpy(
                        buffer,
                        INBUFFER(state).buffer+DATA(state)->offset,
                        slice
                        );

                buffer+=slice;
                len-=slice;
                copied+=slice;

                pthread_mutex_lock(&DATA(state)->mutex);
                DATA(state)->offset+=slice;
                newbuffer = DATA(state)->in_buffer;

                if (DATA(state)->offset >= INBUFFER(state).len) {
                        INBUFFER(state).state = EMPTY;
                        pthread_cond_signal(&DATA(state)->space_avail);
                        newbuffer = (newbuffer+1) % BUFFERS;
                        DATA(state)->offset = 0;
                }

                pthread_mutex_unlock(&DATA(state)->mutex);

                DATA(state)->in_buffer = newbuffer;
        }
        return copied;
}

static void thread_close(io_t *io)
{
        pthread_mutex_lock(&DATA(io)->mutex);
        DATA(io)->closing = true;
        pthread_cond_signal(&DATA(io)->space_avail);
        pthread_mutex_unlock(&DATA(io)->mutex);

        /* Wait for the thread to exit */
        pthread_join(DATA(io)->producer, NULL);
        free(DATA(io));
        free(io);
}

io_source_t thread_source = {
        "thread",
        thread_read,
        NULL,   /* peek */
        NULL,   /* tell */
        NULL,   /* seek */
        thread_close
};