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Add evbuffer_add_file_segment() so one fd can be used efficiently in more than one evbuffer_add_file at a time

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This commit is contained in:
Nick Mathewson 2010-10-21 19:45:49 -04:00
parent 076680abe4
commit e72afae068
4 changed files with 400 additions and 309 deletions
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505
buffer.c
View File

@ -63,6 +63,10 @@
#ifdef _EVENT_HAVE_SYS_SENDFILE_H #ifdef _EVENT_HAVE_SYS_SENDFILE_H
#include <sys/sendfile.h> #include <sys/sendfile.h>
#endif #endif
#ifdef _EVENT_HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <errno.h> #include <errno.h>
#include <stdio.h> #include <stdio.h>
@ -111,14 +115,6 @@
#define SENDFILE_IS_SOLARIS 1 #define SENDFILE_IS_SOLARIS 1
#endif #endif
#ifdef USE_SENDFILE
static int use_sendfile = 1;
#endif
#ifdef _EVENT_HAVE_MMAP
static int use_mmap = 1;
#endif
/* Mask of user-selectable callback flags. */ /* Mask of user-selectable callback flags. */
#define EVBUFFER_CB_USER_FLAGS 0xffff #define EVBUFFER_CB_USER_FLAGS 0xffff
/* Mask of all internal-use-only flags. */ /* Mask of all internal-use-only flags. */
@ -144,13 +140,6 @@ static int evbuffer_ptr_memcmp(const struct evbuffer *buf,
static struct evbuffer_chain *evbuffer_expand_singlechain(struct evbuffer *buf, static struct evbuffer_chain *evbuffer_expand_singlechain(struct evbuffer *buf,
size_t datlen); size_t datlen);
#ifdef WIN32
static int evbuffer_readfile(struct evbuffer *buf, evutil_socket_t fd,
ev_ssize_t howmuch);
#else
#define evbuffer_readfile evbuffer_read
#endif
static struct evbuffer_chain * static struct evbuffer_chain *
evbuffer_chain_new(size_t size) evbuffer_chain_new(size_t size)
{ {
@ -187,40 +176,24 @@ evbuffer_chain_free(struct evbuffer_chain *chain)
chain->flags |= EVBUFFER_DANGLING; chain->flags |= EVBUFFER_DANGLING;
return; return;
} }
if (chain->flags & (EVBUFFER_MMAP|EVBUFFER_SENDFILE|
EVBUFFER_REFERENCE)) { if (chain->flags & EVBUFFER_REFERENCE) {
if (chain->flags & EVBUFFER_REFERENCE) { struct evbuffer_chain_reference *info =
struct evbuffer_chain_reference *info = EVBUFFER_CHAIN_EXTRA(
EVBUFFER_CHAIN_EXTRA( struct evbuffer_chain_reference,
struct evbuffer_chain_reference, chain);
chain); if (info->cleanupfn)
if (info->cleanupfn) (*info->cleanupfn)(chain->buffer,
(*info->cleanupfn)(chain->buffer, chain->buffer_len,
chain->buffer_len, info->extra);
info->extra); }
} if (chain->flags & EVBUFFER_FILESEGMENT) {
#ifdef _EVENT_HAVE_MMAP struct evbuffer_chain_file_segment *info =
if (chain->flags & EVBUFFER_MMAP) { EVBUFFER_CHAIN_EXTRA(
struct evbuffer_chain_fd *info = struct evbuffer_chain_file_segment,
EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd, chain);
chain); if (info->segment)
if (munmap(chain->buffer, chain->buffer_len) == -1) evbuffer_file_segment_free(info->segment);
event_warn("%s: munmap failed", __func__);
if (close(info->fd) == -1)
event_warn("%s: close(%d) failed",
__func__, info->fd);
}
#endif
#ifdef USE_SENDFILE
if (chain->flags & EVBUFFER_SENDFILE) {
struct evbuffer_chain_fd *info =
EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd,
chain);
if (close(info->fd) == -1)
event_warn("%s: close(%d) failed",
__func__, info->fd);
}
#endif
} }
mm_free(chain); mm_free(chain);
@ -2124,56 +2097,6 @@ done:
return result; return result;
} }
#ifdef WIN32
static int
evbuffer_readfile(struct evbuffer *buf, evutil_socket_t fd, ev_ssize_t howmuch)
{
int result;
int nchains, n;
struct evbuffer_iovec v[2];
EVBUFFER_LOCK(buf);
if (buf->freeze_end) {
result = -1;
goto done;
}
if (howmuch < 0)
howmuch = 16384;
/* XXX we _will_ waste some space here if there is any space left
* over on buf->last. */
nchains = evbuffer_reserve_space(buf, howmuch, v, 2);
if (nchains < 1 || nchains > 2) {
result = -1;
goto done;
}
n = read((int)fd, v[0].iov_base, (unsigned int)v[0].iov_len);
if (n <= 0) {
result = n;
goto done;
}
v[0].iov_len = (IOV_LEN_TYPE) n; /* XXXX another problem with big n.*/
if (nchains > 1) {
n = read((int)fd, v[1].iov_base, (unsigned int)v[1].iov_len);
if (n <= 0) {
result = (unsigned long) v[0].iov_len;
evbuffer_commit_space(buf, v, 1);
goto done;
}
v[1].iov_len = n;
}
evbuffer_commit_space(buf, v, nchains);
result = n;
done:
EVBUFFER_UNLOCK(buf);
return result;
}
#endif
#ifdef USE_IOVEC_IMPL #ifdef USE_IOVEC_IMPL
static inline int static inline int
evbuffer_write_iovec(struct evbuffer *buffer, evutil_socket_t fd, evbuffer_write_iovec(struct evbuffer *buffer, evutil_socket_t fd,
@ -2225,44 +2148,46 @@ evbuffer_write_iovec(struct evbuffer *buffer, evutil_socket_t fd,
#ifdef USE_SENDFILE #ifdef USE_SENDFILE
static inline int static inline int
evbuffer_write_sendfile(struct evbuffer *buffer, evutil_socket_t fd, evbuffer_write_sendfile(struct evbuffer *buffer, evutil_socket_t dest_fd,
ev_ssize_t howmuch) ev_ssize_t howmuch)
{ {
struct evbuffer_chain *chain = buffer->first; struct evbuffer_chain *chain = buffer->first;
struct evbuffer_chain_fd *info = struct evbuffer_chain_file_segment *info =
EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd, chain); EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_file_segment,
chain);
const int source_fd = info->segment->fd;
#if defined(SENDFILE_IS_MACOSX) || defined(SENDFILE_IS_FREEBSD) #if defined(SENDFILE_IS_MACOSX) || defined(SENDFILE_IS_FREEBSD)
int res; int res;
off_t len = chain->off; ev_off_t len = chain->off;
#elif defined(SENDFILE_IS_LINUX) || defined(SENDFILE_IS_SOLARIS) #elif defined(SENDFILE_IS_LINUX) || defined(SENDFILE_IS_SOLARIS)
ev_ssize_t res; ev_ssize_t res;
off_t offset = chain->misalign; ev_off_t offset = chain->misalign;
#endif #endif
ASSERT_EVBUFFER_LOCKED(buffer); ASSERT_EVBUFFER_LOCKED(buffer);
#if defined(SENDFILE_IS_MACOSX) #if defined(SENDFILE_IS_MACOSX)
res = sendfile(info->fd, fd, chain->misalign, &len, NULL, 0); res = sendfile(source_fd, dest_fd, chain->misalign, &len, NULL, 0);
if (res == -1 && !EVUTIL_ERR_RW_RETRIABLE(errno)) if (res == -1 && !EVUTIL_ERR_RW_RETRIABLE(errno))
return (-1); return (-1);
return (len); return (len);
#elif defined(SENDFILE_IS_FREEBSD) #elif defined(SENDFILE_IS_FREEBSD)
res = sendfile(info->fd, fd, chain->misalign, chain->off, NULL, &len, 0); res = sendfile(source_fd, dest_fd, chain->misalign, chain->off, NULL, &len, 0);
if (res == -1 && !EVUTIL_ERR_RW_RETRIABLE(errno)) if (res == -1 && !EVUTIL_ERR_RW_RETRIABLE(errno))
return (-1); return (-1);
return (len); return (len);
#elif defined(SENDFILE_IS_LINUX) #elif defined(SENDFILE_IS_LINUX)
/* TODO(niels): implement splice */ /* TODO(niels): implement splice */
res = sendfile(fd, info->fd, &offset, chain->off); res = sendfile(dest_fd, source_fd, &offset, chain->off);
if (res == -1 && EVUTIL_ERR_RW_RETRIABLE(errno)) { if (res == -1 && EVUTIL_ERR_RW_RETRIABLE(errno)) {
/* if this is EAGAIN or EINTR return 0; otherwise, -1 */ /* if this is EAGAIN or EINTR return 0; otherwise, -1 */
return (0); return (0);
} }
return (res); return (res);
#elif defined(SENDFILE_IS_SOLARIS) #elif defined(SENDFILE_IS_SOLARIS)
res = sendfile(fd, info->fd, &offset, chain->off); res = sendfile(dest_fd, source_fd, &offset, chain->off);
if (res == -1 && EVUTIL_ERR_RW_RETRIABLE(errno)) { if (res == -1 && EVUTIL_ERR_RW_RETRIABLE(errno)) {
/* if this is EAGAIN or EINTR return 0; otherwise, -1 */ /* if this is EAGAIN or EINTR return 0; otherwise, -1 */
return (0); return (0);
@ -2654,153 +2579,226 @@ done:
return result; return result;
} }
/* TODO(niels): maybe we don't want to own the fd, however, in that
* case, we should dup it - dup is cheap. Perhaps, we should use a
* callback instead?
*/
/* TODO(niels): we may want to add to automagically convert to mmap, in /* TODO(niels): we may want to add to automagically convert to mmap, in
* case evbuffer_remove() or evbuffer_pullup() are being used. * case evbuffer_remove() or evbuffer_pullup() are being used.
*/ */
int struct evbuffer_file_segment *
evbuffer_add_file(struct evbuffer *outbuf, int fd, evbuffer_file_segment_new(
ev_off_t offset, ev_off_t length) int fd, ev_off_t offset, ev_off_t length, unsigned flags)
{ {
#if defined(USE_SENDFILE) || defined(_EVENT_HAVE_MMAP) struct evbuffer_file_segment *seg =
struct evbuffer_chain *chain; mm_calloc(sizeof(struct evbuffer_file_segment), 1);
struct evbuffer_chain_fd *info; if (!seg)
return NULL;
seg->refcnt = 1;
seg->fd = fd;
seg->flags = flags;
#ifdef WIN32
#define lseek _lseeki64
#define fstat _fstat
#define stat _stat
#endif #endif
int ok = 1; if (length == -1) {
struct stat st;
if (fstat(fd, &st) < 0)
goto err;
length = st.st_size;
}
seg->length = length;
#if defined(USE_SENDFILE) #if defined(USE_SENDFILE)
if (use_sendfile) { if (!(flags & EVBUF_FS_DISABLE_SENDFILE)) {
chain = evbuffer_chain_new(sizeof(struct evbuffer_chain_fd)); seg->offset = offset;
if (chain == NULL) { seg->type = EVBUF_FS_SENDFILE;
event_warn("%s: out of memory", __func__); goto done;
return (-1); }
}
chain->flags |= EVBUFFER_SENDFILE | EVBUFFER_IMMUTABLE;
chain->buffer = NULL; /* no reading possible */
chain->buffer_len = length + offset;
chain->off = length;
chain->misalign = offset;
info = EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd, chain);
info->fd = fd;
EVBUFFER_LOCK(outbuf);
if (outbuf->freeze_end) {
mm_free(chain);
ok = 0;
} else {
outbuf->n_add_for_cb += length;
evbuffer_chain_insert(outbuf, chain);
}
} else
#endif #endif
#if defined(_EVENT_HAVE_MMAP) #if defined(_EVENT_HAVE_MMAP)
if (use_mmap) { /* TODO: Implement an mmap-alike for windows. */
void *mapped = mmap(NULL, length + offset, PROT_READ, if (!(flags & EVBUF_FS_DISABLE_MMAP)) {
#ifdef MAP_NOCACHE
MAP_NOCACHE |
#endif
#ifdef MAP_FILE
MAP_FILE |
#endif
MAP_PRIVATE,
fd, 0);
/* some mmap implementations require offset to be a multiple of /* some mmap implementations require offset to be a multiple of
* the page size. most users of this api, are likely to use 0 * the page size. most users of this api, are likely to use 0
* so mapping everything is not likely to be a problem. * so mapping everything is not likely to be a problem.
* TODO(niels): determine page size and round offset to that * TODO(niels): determine page size and round offset to that
* page size to avoid mapping too much memory. * page size to avoid mapping too much memory.
*/ */
void *mapped = mmap(NULL, length + offset, PROT_READ,
#ifdef MAP_NOCACHE
MAP_NOCACHE | /* ??? */
#endif
#ifdef MAP_FILE
MAP_FILE |
#endif
MAP_PRIVATE,
fd, 0);
if (mapped == MAP_FAILED) { if (mapped == MAP_FAILED) {
event_warn("%s: mmap(%d, %d, %zu) failed", event_warn("%s: mmap(%d, %d, %zu) failed",
__func__, fd, 0, (size_t)(offset + length)); __func__, fd, 0, (size_t)(offset + length));
return (-1);
}
chain = evbuffer_chain_new(sizeof(struct evbuffer_chain_fd));
if (chain == NULL) {
event_warn("%s: out of memory", __func__);
munmap(mapped, length);
return (-1);
}
chain->flags |= EVBUFFER_MMAP | EVBUFFER_IMMUTABLE;
chain->buffer = mapped;
chain->buffer_len = length + offset;
chain->off = length + offset;
info = EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_fd, chain);
info->fd = fd;
EVBUFFER_LOCK(outbuf);
if (outbuf->freeze_end) {
info->fd = -1;
evbuffer_chain_free(chain);
ok = 0;
} else { } else {
outbuf->n_add_for_cb += length; seg->mapping = mapped;
seg->contents = ((char*)mapped)+offset;
evbuffer_chain_insert(outbuf, chain); seg->offset = offset;
seg->type = EVBUF_FS_MMAP;
/* we need to subtract whatever we don't need */ goto done;
evbuffer_drain(outbuf, offset);
}
} else
#endif
{
/* the default implementation */
struct evbuffer *tmp = evbuffer_new();
ev_ssize_t read;
if (tmp == NULL)
return (-1);
#ifdef WIN32
#define lseek _lseeki64
#endif
if (lseek(fd, offset, SEEK_SET) == -1) {
evbuffer_free(tmp);
return (-1);
}
/* we add everything to a temporary buffer, so that we
* can abort without side effects if the read fails.
*/
while (length) {
read = evbuffer_readfile(tmp, fd, (ev_ssize_t)length);
if (read == -1) {
evbuffer_free(tmp);
return (-1);
}
length -= read;
}
EVBUFFER_LOCK(outbuf);
if (outbuf->freeze_end) {
evbuffer_free(tmp);
ok = 0;
} else {
evbuffer_add_buffer(outbuf, tmp);
evbuffer_free(tmp);
#ifdef WIN32
#define close _close
#endif
close(fd);
} }
} }
#endif
if (ok) {
evbuffer_invoke_callbacks(outbuf); ev_off_t start_pos = lseek(fd, 0, SEEK_CUR), pos;
EVBUFFER_UNLOCK(outbuf); ev_off_t read_so_far = 0;
char *mem;
int e;
ev_ssize_t n = 0;
if (!(mem = mm_malloc(length)))
goto err;
if (start_pos < 0) {
mm_free(mem);
goto err;
}
if (lseek(fd, offset, SEEK_SET) < 0) {
mm_free(mem);
goto err;
}
while (read_so_far < length) {
n = read(fd, mem+read_so_far, length-read_so_far);
if (n <= 0)
break;
read_so_far += n;
}
return ok ? 0 : -1; e = errno;
pos = lseek(fd, start_pos, SEEK_SET);
if (n < 0 || (n == 0 && length > read_so_far)) {
mm_free(mem);
errno = e;
goto err;
} else if (pos < 0) {
mm_free(mem);
goto err;
}
seg->contents = mem;
seg->type = EVBUF_FS_IO;
}
done:
if (!(flags & EVBUF_FS_DISABLE_LOCKING)) {
EVTHREAD_ALLOC_LOCK(seg->lock, 0);
}
return seg;
err:
mm_free(seg);
return NULL;
} }
void
evbuffer_file_segment_free(struct evbuffer_file_segment *seg)
{
int refcnt;
EVLOCK_LOCK(seg->lock, 0);
refcnt = --seg->refcnt;
EVLOCK_UNLOCK(seg->lock, 0);
if (refcnt > 0)
return;
EVUTIL_ASSERT(refcnt == 0);
if (seg->type == EVBUF_FS_SENDFILE) {
;
} else if (seg->type == EVBUF_FS_MMAP) {
if (munmap(seg->mapping, seg->length) == -1)
event_warn("%s: munmap failed", __func__);
} else {
EVUTIL_ASSERT(seg->type == EVBUF_FS_IO);
mm_free(seg->contents);
}
if ((seg->flags & EVBUF_FS_CLOSE_ON_FREE) && seg->fd >= 0) {
close(seg->fd);
}
EVTHREAD_FREE_LOCK(seg->lock, 0);
mm_free(seg);
}
int
evbuffer_add_file_segment(struct evbuffer *buf,
struct evbuffer_file_segment *seg, ev_off_t offset, ev_off_t length)
{
struct evbuffer_chain *chain;
struct evbuffer_chain_file_segment *extra;
EVLOCK_LOCK(seg->lock, 0);
++seg->refcnt;
EVLOCK_UNLOCK(seg->lock, 0);
EVBUFFER_LOCK(buf);
if (buf->freeze_end)
goto err;
if (length < 0) {
if (offset > seg->length)
goto err;
length = seg->length - offset;
}
/* Can we actually add this? */
if (offset+length > seg->length)
goto err;
chain = evbuffer_chain_new(sizeof(struct evbuffer_chain_file_segment));
if (!chain)
goto err;
extra = EVBUFFER_CHAIN_EXTRA(struct evbuffer_chain_file_segment, chain);
chain->flags |= EVBUFFER_IMMUTABLE|EVBUFFER_FILESEGMENT;
if (seg->type == EVBUF_FS_SENDFILE) {
chain->flags |= EVBUFFER_SENDFILE;
chain->misalign = seg->offset + offset;
chain->off = length;
chain->buffer_len = chain->misalign + length;
} else if (seg->type == EVBUF_FS_MMAP) {
chain->buffer = (unsigned char*)(seg->contents + offset);
chain->buffer_len = length;
chain->off = length;
} else {
EVUTIL_ASSERT(seg->type == EVBUF_FS_IO);
chain->buffer = (unsigned char*)(seg->contents + offset);
chain->buffer_len = length;
chain->off = length;
}
extra->segment = seg;
buf->n_add_for_cb += length;
evbuffer_chain_insert(buf, chain);
evbuffer_invoke_callbacks(buf);
EVBUFFER_UNLOCK(buf);
return 0;
err:
EVBUFFER_UNLOCK(buf);
evbuffer_file_segment_free(seg);
return -1;
}
int
evbuffer_add_file(struct evbuffer *buf, int fd, ev_off_t offset, ev_off_t length)
{
struct evbuffer_file_segment *seg;
unsigned flags = EVBUF_FS_CLOSE_ON_FREE;
int r;
seg = evbuffer_file_segment_new(fd, offset, length, flags);
if (!seg)
return -1;
r = evbuffer_add_file_segment(buf, seg, 0, length);
evbuffer_file_segment_free(seg);
return r;
}
void void
evbuffer_setcb(struct evbuffer *buffer, evbuffer_cb cb, void *cbarg) evbuffer_setcb(struct evbuffer *buffer, evbuffer_cb cb, void *cbarg)
@ -2936,50 +2934,3 @@ evbuffer_cb_unsuspend(struct evbuffer *buffer, struct evbuffer_cb_entry *cb)
} }
#endif #endif
/* These hooks are exposed so that the unit tests can temporarily disable
* sendfile support in order to test mmap, or both to test linear
* access. Don't use it; if we need to add a way to disable sendfile support
* in the future, it will probably be via an alternate version of
* evbuffer_add_file() with a 'flags' argument.
*/
int _evbuffer_testing_use_sendfile(void);
int _evbuffer_testing_use_mmap(void);
int _evbuffer_testing_use_linear_file_access(void);
int
_evbuffer_testing_use_sendfile(void)
{
int ok = 0;
#ifdef USE_SENDFILE
use_sendfile = 1;
ok = 1;
#endif
#ifdef _EVENT_HAVE_MMAP
use_mmap = 0;
#endif
return ok;
}
int
_evbuffer_testing_use_mmap(void)
{
int ok = 0;
#ifdef USE_SENDFILE
use_sendfile = 0;
#endif
#ifdef _EVENT_HAVE_MMAP
use_mmap = 1;
ok = 1;
#endif
return ok;
}
int
_evbuffer_testing_use_linear_file_access(void)
{
#ifdef USE_SENDFILE
use_sendfile = 0;
#endif
#ifdef _EVENT_HAVE_MMAP
use_mmap = 0;
#endif
return 1;
}

48
evbuffer-internal.h
View File

@ -170,8 +170,8 @@ struct evbuffer_chain {
/** Set if special handling is required for this chain */ /** Set if special handling is required for this chain */
unsigned flags; unsigned flags;
#define EVBUFFER_MMAP 0x0001 /**< memory in buffer is mmaped */ #define EVBUFFER_FILESEGMENT 0x0001 /**< A chain used for a file segment */
#define EVBUFFER_SENDFILE 0x0002 /**< a chain used for sendfile */ #define EVBUFFER_SENDFILE 0x0002 /**< a chain used with sendfile */
#define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */ #define EVBUFFER_REFERENCE 0x0004 /**< a chain with a mem reference */
#define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */ #define EVBUFFER_IMMUTABLE 0x0008 /**< read-only chain */
/** a chain that mustn't be reallocated or freed, or have its contents /** a chain that mustn't be reallocated or freed, or have its contents
@ -192,21 +192,45 @@ struct evbuffer_chain {
unsigned char *buffer; unsigned char *buffer;
}; };
/* this is currently used by both mmap and sendfile */ /** callback for a reference chain; lets us know what to do with it when
/* TODO(niels): something strange needs to happen for Windows here, I am not * we're done with it. Lives at the end of an evbuffer_chain with the
* sure what that is, but it needs to get looked into. * EVBUFFER_REFERENCE flag set */
*/
struct evbuffer_chain_fd {
int fd; /**< the fd associated with this chain */
};
/** callback for a reference buffer; lets us know what to do with it when
* we're done with it. */
struct evbuffer_chain_reference { struct evbuffer_chain_reference {
evbuffer_ref_cleanup_cb cleanupfn; evbuffer_ref_cleanup_cb cleanupfn;
void *extra; void *extra;
}; };
/** File segment for a file-segment chain. Lives at the end of an
* evbuffer_chain with the EVBUFFER_FILESEGMENT flag set. */
struct evbuffer_chain_file_segment {
struct evbuffer_file_segment *segment;
};
/* Declared in event2/buffer.h; defined here. */
struct evbuffer_file_segment {
void *lock; /**< lock prevent concurrent access to refcnt */
int refcnt; /**< Reference count for this file segment */
unsigned flags; /**< combination of EVBUF_FS_* flags */
/** What kind of file segment is this? */
enum {EVBUF_FS_MMAP, EVBUF_FS_SENDFILE, EVBUF_FS_IO} type;
/** The fd that we read the data from. */
int fd;
/** If we're using mmap, this is the raw mapped memory. */
void *mapping;
/** If we're using mmap or IO, this is the content of the file
* segment. */
char *contents;
/** If we're using mmap, this is the offset within 'mapping' where
* this data segment begins. If we're using sendfile, this is the
* offset within the file where this data begins. If we're using IO,
* this is 0. */
off_t offset;
/** The length of this segment. */
off_t length;
};
#define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain) #define EVBUFFER_CHAIN_SIZE sizeof(struct evbuffer_chain)
/** Return a pointer to extra data allocated along with an evbuffer. */ /** Return a pointer to extra data allocated along with an evbuffer. */
#define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1) #define EVBUFFER_CHAIN_EXTRA(t, c) (t *)((struct evbuffer_chain *)(c) + 1)

103
include/event2/buffer.h
View File

@ -368,16 +368,117 @@ int evbuffer_add_reference(struct evbuffer *outbuf,
The results of using evbuffer_remove() or evbuffer_pullup() are The results of using evbuffer_remove() or evbuffer_pullup() are
undefined. undefined.
For more fine-grained control, use evbuffer_add_file_segment.
@param outbuf the output buffer @param outbuf the output buffer
@param fd the file descriptor @param fd the file descriptor
@param off the offset from which to read data @param off the offset from which to read data
@param length how much data to read @param length how much data to read, or -1 to read as much as possible.
(-1 requires that 'fd' support fstat.)
@return 0 if successful, or -1 if an error occurred @return 0 if successful, or -1 if an error occurred
*/ */
int evbuffer_add_file(struct evbuffer *output, int fd, ev_off_t offset, int evbuffer_add_file(struct evbuffer *output, int fd, ev_off_t offset,
ev_off_t length); ev_off_t length);
/**
An evbuffer_file_segment holds a reference to a range of a file --
possibly the whole file! -- for use in writing from an evbuffer to a
socket. It could be implemented with mmap, sendfile, splice, or (if all
else fails) by just pulling all the data into RAM. A single
evbuffer_file_segment can be added more than once, and to more than one
evbuffer.
*/
struct evbuffer_file_segment;
/**
Flag for creating evbuffer_file_segment: If this flag is set, then when
the evbuffer_file_segment is freed and no longer in use by any
evbuffer, the underlying fd is closed.
*/
#define EVBUF_FS_CLOSE_ON_FREE 0x01
/**
Flag for creating evbuffer_file_segment: Disable memory-map based
implementations.
*/
#define EVBUF_FS_DISABLE_MMAP 0x02
/**
Flag for creating evbuffer_file_segment: Disable direct fd-to-fd
implementations (including sendfile and splice).
You might want to use this option if data needs to be taken from the
evbuffer by any means other than writing it to the network: the sendfile
backend is fast, but it only works for sending files directly to the
network.
*/
#define EVBUF_FS_DISABLE_SENDFILE 0x04
/**
Flag for creating evbuffer_file_segment: Do not allocate a lock for this
segment. If this option is set, then neither the segment nor any
evbuffer it is added to may ever be accessed from more than one thread
at a time.
*/
#define EVBUF_FS_DISABLE_LOCKING 0x08
/**
Create and return a new evbuffer_file_segment for reading data from a
file and sending it out via an evbuffer.
This function avoids unnecessary data copies between userland and
kernel. Where available, it uses sendfile or splice.
The file descriptor must not be closed so long as any evbuffer is using
this segment.
The results of using evbuffer_remove() or evbuffer_pullup() or any other
function that reads bytes from an evbuffer on any evbuffer containing
the newly returned segment are undefined, unless you pass the
EVBUF_FS_DISABLE_SENDFILE flag to this function.
@param fd an open file to read from.
@param offset an index within the file at which to start reading
@param length how much data to read, or -1 to read as much as possible.
(-1 requires that 'fd' support fstat.)
@param flags any number of the EVBUF_FS_* flags
@return a new evbuffer_file_segment, or NULL on failure.
**/
struct evbuffer_file_segment *evbuffer_file_segment_new(
int fd, ev_off_t offset, ev_off_t length, unsigned flags);
/**
Free an evbuffer_file_segment
It is safe to call this function even if the segment has been added to
one or more evbuffers. The evbuffer_file_segment will not be freed
until no more references to it exist.
*/
void evbuffer_file_segment_free(struct evbuffer_file_segment *seg);
/**
Insert some or all of an evbuffer_file_segment at the end of an evbuffer
Note that the offset and length parameters of this function have a
different meaning from those provided to evbuffer_file_segment_new: When
you create the segment, the offset is the offset _within the file_, and
the length is the length _of the segment_, whereas when you add a
segment to an evbuffer, the offset is _within the segment_ and the
length is the length of the _part of the segment you want to use.
In other words, if you have a 10 KiB file, and you create an
evbuffer_file_segment for it with offset 20 and length 1000, it will
refer to bytes 20..1019 inclusive. If you then pass this segment to
evbuffer_add_file_segment and specify an offset of 20 and a length of
50, you will be adding bytes 40..99 inclusive.
@param buf the evbuffer to append to
@param seg the segment to add
@param offset the offset within the segment to start from
@param length the amount of data to add, or -1 to add it all.
@return 0 on success, -1 on failure.
*/
int evbuffer_add_file_segment(struct evbuffer *buf,
struct evbuffer_file_segment *seg, ev_off_t offset, ev_off_t length);
/** /**
Append a formatted string to the end of an evbuffer. Append a formatted string to the end of an evbuffer.

53
test/regress_buffer.c
View File

@ -583,10 +583,6 @@ test_evbuffer_reference(void *ptr)
evbuffer_free(src); evbuffer_free(src);
} }
int _evbuffer_testing_use_sendfile(void);
int _evbuffer_testing_use_mmap(void);
int _evbuffer_testing_use_linear_file_access(void);
static void static void
test_evbuffer_add_file(void *ptr) test_evbuffer_add_file(void *ptr)
{ {
@ -598,26 +594,39 @@ test_evbuffer_add_file(void *ptr)
int fd = -1; int fd = -1;
evutil_socket_t pair[2] = {-1, -1}; evutil_socket_t pair[2] = {-1, -1};
int r=0, n_written=0; int r=0, n_written=0;
int want_type = 0;
unsigned flags = 0;
int use_segment = 1;
struct evbuffer_file_segment *seg = NULL;
/* Add a test for a big file. XXXX */ /* Add a test for a big file. XXXX */
tt_assert(impl); tt_assert(impl);
if (!strcmp(impl, "sendfile")) { if (!strcmp(impl, "nosegment")) {
if (!_evbuffer_testing_use_sendfile()) use_segment = 0;
tt_skip(); } else if (!strcmp(impl, "sendfile")) {
TT_BLATHER(("Using sendfile-based implementaion")); flags = EVBUF_FS_DISABLE_MMAP;
want_type = EVBUF_FS_SENDFILE;
} else if (!strcmp(impl, "mmap")) { } else if (!strcmp(impl, "mmap")) {
if (!_evbuffer_testing_use_mmap()) flags = EVBUF_FS_DISABLE_SENDFILE;
tt_skip(); want_type = EVBUF_FS_MMAP;
TT_BLATHER(("Using mmap-based implementaion"));
} else if (!strcmp(impl, "linear")) { } else if (!strcmp(impl, "linear")) {
if (!_evbuffer_testing_use_linear_file_access()) flags = EVBUF_FS_DISABLE_SENDFILE|EVBUF_FS_DISABLE_MMAP;
tt_skip(); want_type = EVBUF_FS_IO;
TT_BLATHER(("Using read-based implementaion"));
} else { } else {
TT_DIE(("Didn't recognize the implementation")); TT_DIE(("Didn't recognize the implementation"));
} }
datalen = strlen(data);
fd = regress_make_tmpfile(data, datalen);
if (use_segment) {
seg = evbuffer_file_segment_new(fd, 0, datalen, flags);
tt_assert(seg);
if ((int)seg->type != (int)want_type)
tt_skip();
}
#if defined(_EVENT_HAVE_SENDFILE) && defined(__sun__) && defined(__svr4__) #if defined(_EVENT_HAVE_SENDFILE) && defined(__sun__) && defined(__svr4__)
/* We need to use a pair of AF_INET sockets, since Solaris /* We need to use a pair of AF_INET sockets, since Solaris
doesn't support sendfile() over AF_UNIX. */ doesn't support sendfile() over AF_UNIX. */
@ -628,12 +637,13 @@ test_evbuffer_add_file(void *ptr)
tt_abort_msg("socketpair failed"); tt_abort_msg("socketpair failed");
#endif #endif
datalen = strlen(data);
fd = regress_make_tmpfile(data, datalen);
tt_assert(fd != -1); tt_assert(fd != -1);
tt_assert(evbuffer_add_file(src, fd, 0, datalen) != -1); if (use_segment) {
tt_assert(evbuffer_add_file_segment(src, seg, 0, -1)!=-1);
} else {
tt_assert(evbuffer_add_file(src, fd, 0, -1) != -1);
}
evbuffer_validate(src); evbuffer_validate(src);
@ -650,8 +660,9 @@ test_evbuffer_add_file(void *ptr)
evbuffer_validate(src); evbuffer_validate(src);
compare = (char *)evbuffer_pullup(src, datalen); compare = (char *)evbuffer_pullup(src, datalen);
tt_assert(compare != NULL); tt_assert(compare != NULL);
if (memcmp(compare, data, datalen)) if (memcmp(compare, data, datalen)) {
tt_abort_msg("Data from add_file differs."); tt_abort_msg("Data from add_file differs.");
}
evbuffer_validate(src); evbuffer_validate(src);
end: end:
@ -660,6 +671,8 @@ test_evbuffer_add_file(void *ptr)
if (pair[1] >= 0) if (pair[1] >= 0)
evutil_closesocket(pair[1]); evutil_closesocket(pair[1]);
evbuffer_free(src); evbuffer_free(src);
if (seg)
evbuffer_file_segment_free(seg);
} }
#ifndef _EVENT_DISABLE_MM_REPLACEMENT #ifndef _EVENT_DISABLE_MM_REPLACEMENT
@ -1562,6 +1575,8 @@ struct testcase_t evbuffer_testcases[] = {
(void*)"mmap" }, (void*)"mmap" },
{ "add_file_linear", test_evbuffer_add_file, TT_FORK, &nil_setup, { "add_file_linear", test_evbuffer_add_file, TT_FORK, &nil_setup,
(void*)"linear" }, (void*)"linear" },
{ "add_file_nosegment", test_evbuffer_add_file, TT_FORK, &nil_setup,
(void*)"nosegment" },
END_OF_TESTCASES END_OF_TESTCASES
}; };