翻譯：libevent參考手冊第八章：evbuffer：緩衝IO實用功能 (十) （轉）
阿新 • • 發佈：2018-12-23
{
/* Let's look at the first two chunks of buf, and write them to stderr. */int n, i;
struct evbuffer_iovec v[2];
n = evbuffer_peek(buf, -1, NULL, v, 2);
for (i=0; i<n; ++i) { /* There might be less than two chunks available. */
fwrite(v[i].iov_base, 1, v[i].iov_len, stderr);
}
}
{
struct evbuffer_iovec *v;
size_t written =0;
/* determine how many chunks we need. */
n = evbuffer_peek(buf, 4096, NULL, NULL, 0);
/* Allocate space for the chunks. This would be a good time to use
alloca() if you have it.
v = malloc(sizeof(struct evbuffer_iovec)*n);
/* Actually fill up v. */
n = evbuffer_peek(buf, 4096, NULL, v, n);
for (i=0; i<n; ++i) {
size_t len = v[i].iov_len;
if (written + len >4096)
len =4096- written;
r = write(1/* stdout */, v[i].iov_base, len);
break;
/* We keep track of the bytes written separately; if we don't,
we may write more than 4096 bytes if the last chunk puts
us over the limit. */
written += len;
}
free(v);
}
{
/* Let's get the first 16K of data after the first occurrence of the
string "start\n", and pass it to a consume() function. */struct evbuffer_ptr ptr;
struct evbuffer_iovec v[1];
constchar s[] ="start\n";
int n_written;
ptr = evbuffer_search(buf, s, strlen(s), NULL);
if (ptr.pos ==-1)
return; /* no start string found. *//* Advance the pointer past the start string. */if (evbuffer_ptr_set(buf, &ptr, strlen(s), EVBUFFER_PTR_ADD) <0)
return; /* off the end of the string. */while (n_written <16*1024) {
/* Peek at a single chunk. */if (evbuffer_peek(buf, -1, &ptr, v, 1) <1)
break;
/* Pass the data to some user-defined consume function */
consume(v[0].iov_base, v[0].iov_len);
n_written += v[0].iov_len;
/* Advance the pointer so we see the next chunk next time. */if (evbuffer_ptr_set(buf, &ptr, v[0].iov_len, EVBUFFER_PTR_ADD)<0)
break;
}
}
/* Let's look at the first two chunks of buf, and write them to stderr. */int n, i;
struct evbuffer_iovec v[2];
n = evbuffer_peek(buf, -1, NULL, v, 2);
for (i=0; i<n; ++i) { /* There might be less than two chunks available. */
fwrite(v[i].iov_base, 1, v[i].iov_len, stderr);
}
}
{
struct evbuffer_iovec *v;
size_t written =0;
/* determine how many chunks we need. */
n = evbuffer_peek(buf, 4096, NULL, NULL, 0);
/* Allocate space for the chunks. This would be a good time to use
alloca() if you have it.
v = malloc(sizeof(struct evbuffer_iovec)*n);
/* Actually fill up v. */
n = evbuffer_peek(buf, 4096, NULL, v, n);
for (i=0; i<n; ++i) {
size_t len = v[i].iov_len;
if (written + len >4096)
len =4096- written;
r = write(1/* stdout */, v[i].iov_base, len);
break;
/* We keep track of the bytes written separately; if we don't,
we may write more than 4096 bytes if the last chunk puts
us over the limit. */
written += len;
}
free(v);
}
{
/* Let's get the first 16K of data after the first occurrence of the
string "start\n", and pass it to a consume() function. */struct evbuffer_ptr ptr;
struct evbuffer_iovec v[1];
constchar s[] ="start\n";
int n_written;
ptr = evbuffer_search(buf, s, strlen(s), NULL);
if (ptr.pos ==-1)
return; /* no start string found. *//* Advance the pointer past the start string. */if (evbuffer_ptr_set(buf, &ptr, strlen(s), EVBUFFER_PTR_ADD) <0)
return; /* off the end of the string. */while (n_written <16*1024) {
/* Peek at a single chunk. */if (evbuffer_peek(buf, -1, &ptr, v, 1) <1)
break;
/* Pass the data to some user-defined consume function */
consume(v[0].iov_base, v[0].iov_len);
n_written += v[0].iov_len;
/* Advance the pointer so we see the next chunk next time. */if (evbuffer_ptr_set(buf, &ptr, v[0].iov_len, EVBUFFER_PTR_ADD)<0)
break;
}
}