source: libwandio/ior-thread.c @ 1d4db58

4.0.1-hotfixescachetimestampsdevelopdpdk-ndagetsilivegetfragoffhelplibtrace4ndag_formatpfringrc-4.0.1rc-4.0.2rc-4.0.3rc-4.0.4ringdecrementfixringperformanceringtimestampfixes
Last change on this file since 1d4db58 was 60f3c4c, checked in by Shane Alcock <salcock@…>, 9 years ago
  • Shifted wandio into a separate library, seeing as we're going to be exporting the API now
  • Property mode set to 100644
File size: 7.3 KB
Line 
1/*
2 * This file is part of libtrace
3 *
4 * Copyright (c) 2007,2008,2009,2010 The University of Waikato, Hamilton,
5 * New Zealand.
6 *
7 * Authors: Daniel Lawson
8 *          Perry Lorier
9 *          Shane Alcock
10 *         
11 * All rights reserved.
12 *
13 * This code has been developed by the University of Waikato WAND
14 * research group. For further information please see http://www.wand.net.nz/
15 *
16 * libtrace is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2 of the License, or
19 * (at your option) any later version.
20 *
21 * libtrace is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
24 * GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with libtrace; if not, write to the Free Software
28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
29 *
30 * $Id$
31 *
32 */
33
34
35#include "config.h"
36#include "wandio.h"
37#include <sys/types.h>
38#include <sys/stat.h>
39#include <fcntl.h>
40#include <stdlib.h>
41#include <pthread.h>
42#include <string.h>
43#include <stdbool.h>
44#include <errno.h>
45#ifdef HAVE_SYS_PRCTL_H
46#include <sys/prctl.h>
47#endif
48
49/* Libtrace IO module implementing a threaded reader.
50 *
51 * This module enables another IO reader, called the "parent", to perform its
52 * reading using a separate thread. The reading thread reads data into a
53 * series of 1MB buffers. Once all the buffers are full, it waits for the
54 * main thread to free up some of the buffers by consuming data from them. The
55 * reading thread also uses a pthread condition to indicate to the main thread
56 * that there is data available in the buffers.
57 */
58
59/* 1MB Buffer */
60#define BUFFERSIZE (1024*1024)
61
62extern io_source_t thread_source;
63
64/* This structure defines a single buffer or "slice" */
65struct buffer_t {
66        char buffer[BUFFERSIZE];        /* The buffer itself */
67        int len;                        /* The size of the buffer */
68        enum { EMPTY = 0, FULL = 1 } state;     /* Is the buffer in use? */
69};
70
71struct state_t {
72        /* The collection of buffers (or slices) */
73        struct buffer_t *buffer;
74        /* The index of the buffer to read into next */
75        int in_buffer;
76        /* The read offset into the current buffer */
77        off_t offset;
78        /* The reading thread */
79        pthread_t producer;
80        /* Indicates that there is a free buffer to read into */
81        pthread_cond_t space_avail;
82        /* Indicates that there is data in one of the buffers */
83        pthread_cond_t data_ready;
84        /* The mutex for the read buffers */
85        pthread_mutex_t mutex;
86        /* The parent reader */
87        io_t *io;
88        /* Indicates whether the main thread is concluding */
89        bool closing;
90};
91
92#define DATA(x) ((struct state_t *)((x)->data))
93#define INBUFFER(x) (DATA(x)->buffer[DATA(x)->in_buffer])
94#define min(a,b) ((a)<(b) ? (a) : (b))
95
96/* The reading thread */
97static void *thread_producer(void* userdata)
98{
99        io_t *state = (io_t*) userdata;
100        int buffer=0;
101        bool running = true;
102
103#ifdef PR_SET_NAME
104        char namebuf[17];
105        if (prctl(PR_GET_NAME, namebuf, 0,0,0) == 0) {
106                namebuf[16] = '\0'; /* Make sure it's NUL terminated */
107                /* If the filename is too long, overwrite the last few bytes */
108                if (strlen(namebuf)>9) {
109                        strcpy(namebuf+10,"[ior]");
110                }
111                else {
112                        strncat(namebuf," [ior]",16);
113                }
114                prctl(PR_SET_NAME, namebuf, 0,0,0);
115        }
116#endif
117
118        pthread_mutex_lock(&DATA(state)->mutex);
119        do {
120                /* If all the buffers are full, we need to wait for one to
121                 * become free otherwise we have nowhere to write to! */
122                while (DATA(state)->buffer[buffer].state == FULL) {
123                        if (DATA(state)->closing)
124                                break;
125                        pthread_cond_wait(&DATA(state)->space_avail, &DATA(state)->mutex);
126                }
127
128                /* Don't bother reading any more data if we are shutting up
129                 * shop */
130                if (DATA(state)->closing) {
131                        break;
132                }
133                pthread_mutex_unlock(&DATA(state)->mutex);
134
135                /* Get the parent reader to fill the buffer */
136                DATA(state)->buffer[buffer].len=wandio_read(
137                                DATA(state)->io,
138                                DATA(state)->buffer[buffer].buffer,
139                                sizeof(DATA(state)->buffer[buffer].buffer));
140
141                pthread_mutex_lock(&DATA(state)->mutex);
142
143                DATA(state)->buffer[buffer].state = FULL;
144
145                /* If we've not reached the end of the file keep going */
146                running = (DATA(state)->buffer[buffer].len > 0 );
147
148                /* Signal that there is data available for the main thread */
149                pthread_cond_signal(&DATA(state)->data_ready);
150
151                /* Move on to the next buffer */
152                buffer=(buffer+1) % max_buffers;
153
154        } while(running);
155
156        /* If we reach here, it's all over so start tidying up */
157        wandio_destroy(DATA(state)->io);
158
159        pthread_cond_signal(&DATA(state)->data_ready);
160        pthread_mutex_unlock(&DATA(state)->mutex);
161
162        return NULL;
163}
164
165io_t *thread_open(io_t *parent)
166{
167        io_t *state;
168
169        if (!parent) {
170                return NULL;
171        }
172       
173
174        state = malloc(sizeof(io_t));
175        state->data = calloc(1,sizeof(struct state_t));
176        state->source = &thread_source;
177
178        DATA(state)->buffer = (struct buffer_t *)malloc(sizeof(struct buffer_t) * max_buffers);
179        memset(DATA(state)->buffer, 0, sizeof(struct buffer_t) * max_buffers);
180        DATA(state)->in_buffer = 0;
181        DATA(state)->offset = 0;
182        pthread_mutex_init(&DATA(state)->mutex,NULL);
183        pthread_cond_init(&DATA(state)->data_ready,NULL);
184        pthread_cond_init(&DATA(state)->space_avail,NULL);
185
186        DATA(state)->io = parent;
187        DATA(state)->closing = false;
188
189        /* Create the reading thread */
190        pthread_create(&DATA(state)->producer,NULL,thread_producer,state);
191
192        return state;
193}
194
195static off_t thread_read(io_t *state, void *buffer, off_t len)
196{
197        int slice;
198        int copied=0;
199        int newbuffer;
200
201        while(len>0) {
202                pthread_mutex_lock(&DATA(state)->mutex);
203               
204                /* Wait for the reader thread to provide us with some data */
205                while (INBUFFER(state).state == EMPTY) {
206                        ++read_waits;
207                        pthread_cond_wait(&DATA(state)->data_ready, &DATA(state)->mutex);
208
209                }
210               
211                /* Check for errors and EOF */
212                if (INBUFFER(state).len <1) {
213
214                        if (copied<1) {
215                                errno=EIO; /* FIXME: Preserve the errno from the other thread */
216                                copied = INBUFFER(state).len;
217                        }
218
219                        pthread_mutex_unlock(&DATA(state)->mutex);
220                        return copied;
221                }
222
223                /* Copy the next available slice into the main buffer */
224                slice=min( INBUFFER(state).len-DATA(state)->offset,len);
225
226                pthread_mutex_unlock(&DATA(state)->mutex);
227                               
228                memcpy(
229                        buffer,
230                        INBUFFER(state).buffer+DATA(state)->offset,
231                        slice
232                        );
233
234                buffer+=slice;
235                len-=slice;
236                copied+=slice;
237
238                pthread_mutex_lock(&DATA(state)->mutex);
239                DATA(state)->offset+=slice;
240                newbuffer = DATA(state)->in_buffer;
241               
242                /* If we've read everything from the current slice, let the
243                 * read thread know that there is now more space available
244                 * and start reading from the next slice */
245                if (DATA(state)->offset >= INBUFFER(state).len) {
246                        INBUFFER(state).state = EMPTY;
247                        pthread_cond_signal(&DATA(state)->space_avail);
248                        newbuffer = (newbuffer+1) % max_buffers;
249                        DATA(state)->offset = 0;
250                }
251
252                pthread_mutex_unlock(&DATA(state)->mutex);
253
254                DATA(state)->in_buffer = newbuffer;
255        }
256        return copied;
257}
258
259static void thread_close(io_t *io)
260{
261        pthread_mutex_lock(&DATA(io)->mutex);
262        DATA(io)->closing = true;
263        pthread_cond_signal(&DATA(io)->space_avail);
264        pthread_mutex_unlock(&DATA(io)->mutex);
265
266        /* Wait for the thread to exit */
267        pthread_join(DATA(io)->producer, NULL);
268        free(DATA(io)->buffer);
269        free(DATA(io));
270        free(io);
271}
272
273io_source_t thread_source = {
274        "thread",
275        thread_read,
276        NULL,   /* peek */
277        NULL,   /* tell */
278        NULL,   /* seek */
279        thread_close
280};
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