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msg: introduce partial line buffers per mp_log 

The goal is reducing log messups (which happen surprisingly often) by
buffering partial lines in mp_log. This is still not 100% reliable, but
better.

The extrabuffers for MSGL_STATUS and MSGL_STATS are not needed anymore,
because a separate mp_log instance can be used if problems really occur.

Also, give up, and replace the snprintf acrobatics with bstr.

mp_log.partial has a quite subtle problem wrt. talloc: talloc parents
can not be used, because there's no lock around the internal talloc
structures associated with mp_log. Thus it has to be freed manually,
even if this happens through a talloc destructor.
This commit is contained in:
wm4 2016-03-01 22:34:14 +01:00
parent a5eef06225
commit 46a3165cde
1 changed files with 27 additions and 24 deletions
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51
common/msg.c
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@ -31,6 +31,7 @@
#include "common/common.h"
#include "common/global.h"
#include "misc/ring.h"
#include "misc/bstr.h"
#include "options/options.h"
#include "osdep/terminal.h"
#include "osdep/io.h"
@ -64,7 +65,7 @@ struct mp_log_root {
* synchronized mp_log tree.) */
atomic_ulong reload_counter;
// --- protected by mp_msg_lock
char *buffer;
bstr buffer;
};
struct mp_log {
@ -74,6 +75,7 @@ struct mp_log {
int level; // minimum log level for any outputs
int terminal_level; // minimum log level for terminal output
atomic_ulong reload_counter;
char *partial;
};
struct mp_log_buffer {
@ -335,27 +337,17 @@ void mp_msg_va(struct mp_log *log, int lev, const char *format, va_list va)
pthread_mutex_lock(&mp_msg_lock);
// MSGL_STATUS and MSGL_STATS use their own buffer; this prevents clashes
// with mp_msg() users which do not properly send complete lines only.
char tmp[256];
bool use_tmp = lev == MSGL_STATUS || lev == MSGL_STATS;
struct mp_log_root *root = log->root;
char *text = use_tmp ? tmp : root->buffer;
int len = use_tmp ? 0 : strlen(text);
int max_len = use_tmp ? sizeof(tmp) : talloc_get_size(text);
va_list t;
va_copy(t, va);
int res = vsnprintf(text + len, max_len - len, format, t);
if (res >= 0 && res >= max_len - len && !use_tmp) {
root->buffer = talloc_realloc(root, root->buffer, char, res + len + 1);
text = root->buffer;
max_len = talloc_get_size(text);
res = vsnprintf(text + len, max_len - len, format, va);
}
if (res < 0)
text = "[fprintf error]\n";
root->buffer.len = 0;
if (log->partial[0])
bstr_xappend_asprintf(root, &root->buffer, "%s", log->partial);
log->partial[0] = '\0';
bstr_xappend_vasprintf(root, &root->buffer, format, va);
char *text = root->buffer.start;
if (lev == MSGL_STATS) {
dump_stats(log, lev, text);
@ -384,15 +376,25 @@ void mp_msg_va(struct mp_log *log, int lev, const char *format, va_list va)
if (lev == MSGL_STATUS) {
if (text[0])
print_terminal_line(log, lev, text, root->termosd ? "\r" : "\n");
} else {
int leftover = strlen(text);
memmove(root->buffer, text, leftover + 1);
} else if (text[0]) {
int size = strlen(text) + 1;
if (talloc_get_size(log->partial) < size)
log->partial = talloc_realloc(NULL, log->partial, char, size);
memcpy(log->partial, text, size);
}
}
pthread_mutex_unlock(&mp_msg_lock);
}
static void destroy_log(void *ptr)
{
struct mp_log *log = ptr;
// This is not managed via talloc itself, because mp_msg calls must be
// thread-safe, while talloc is not thread-safe.
talloc_free(log->partial);
}
// Create a new log context, which uses talloc_ctx as talloc parent, and parent
// as logical parent.
// The name is the prefix put before the output. It's usually prefixed by the
@ -409,7 +411,9 @@ struct mp_log *mp_log_new(void *talloc_ctx, struct mp_log *parent,
struct mp_log *log = talloc_zero(talloc_ctx, struct mp_log);
if (!parent->root)
return log; // same as null_log
talloc_set_destructor(log, destroy_log);
log->root = parent->root;
log->partial = talloc_strdup(NULL, "");
if (name) {
if (name[0] == '!') {
name = &name[1];
@ -443,7 +447,6 @@ void mp_msg_init(struct mpv_global *global)
*root = (struct mp_log_root){
.global = global,
.reload_counter = ATOMIC_VAR_INIT(1),
.buffer = talloc_strdup(root, ""),
};
struct mp_log dummy = { .root = root };