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filesrc: remove MMAP code

Browse source 
Remove the mmap code, it was disabled and probably needs a complete rewrite
anyway if this is to be ported to 0.11.
This commit is contained in:
Wim Taymans 2011-06-07 17:03:09 +02:00
parent 78ea732149
commit 72d0a830ff
2 changed files with 9 additions and 502 deletions
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502
plugins/elements/gstfilesrc.c
View file

@ -63,10 +63,6 @@
# include <unistd.h>
#endif
#ifdef HAVE_MMAP
# include <sys/mman.h>
#endif
#include <errno.h>
#include <string.h>
@ -119,46 +115,6 @@ gst_open (const gchar * filename, int flags, int mode)
#endif
}
/**********************************************************************
* GStreamer Default File Source
* Theory of Operation
*
* Update: see GstFileSrc:use-mmap property documentation below
* for why use of mmap() is disabled by default.
*
* This source uses mmap(2) to efficiently load data from a file.
* To do this without seriously polluting the applications' memory
* space, it must do so in smaller chunks, say 1-4MB at a time.
* Buffers are then subdivided from these mmap'd chunks, to directly
* make use of the mmap.
*
* To handle refcounting so that the mmap can be freed at the appropriate
* time, a buffer will be created for each mmap'd region, and all new
* buffers will be sub-buffers of this top-level buffer. As they are
* freed, the refcount goes down on the mmap'd buffer and its free()
* function is called, which will call munmap(2) on itself.
*
* If a buffer happens to cross the boundaries of an mmap'd region, we
* have to decide whether it's more efficient to copy the data into a
* new buffer, or mmap() just that buffer. There will have to be a
* breakpoint size to determine which will be done. The mmap() size
* has a lot to do with this as well, because you end up in double-
* jeopardy: the larger the outgoing buffer, the more data to copy when
* it overlaps, *and* the more frequently you'll have buffers that *do*
* overlap.
*
* Seeking is another tricky aspect to do efficiently. The initial
* implementation of this source won't make use of these features, however.
* The issue is that if an application seeks backwards in a file, *and*
* that region of the file is covered by an mmap that hasn't been fully
* deallocated, we really should re-use it. But keeping track of these
* regions is tricky because we have to lock the structure that holds
* them. We need to settle on a locking primitive (GMutex seems to be
* a really good option...), then we can do that.
*/
GST_DEBUG_CATEGORY_STATIC (gst_file_src_debug);
#define GST_CAT_DEFAULT gst_file_src_debug
@ -170,20 +126,12 @@ enum
};
#define DEFAULT_BLOCKSIZE 4*1024
#define DEFAULT_MMAPSIZE 4*1024*1024
#define DEFAULT_TOUCH TRUE
#define DEFAULT_USEMMAP FALSE
#define DEFAULT_SEQUENTIAL FALSE
enum
{
ARG_0,
ARG_LOCATION,
ARG_FD,
ARG_MMAPSIZE,
ARG_SEQUENTIAL,
ARG_TOUCH,
ARG_USEMMAP
PROP_0,
PROP_LOCATION,
PROP_FD
};
static void gst_file_src_finalize (GObject * object);
@ -225,55 +173,15 @@ gst_file_src_class_init (GstFileSrcClass * klass)
gobject_class->set_property = gst_file_src_set_property;
gobject_class->get_property = gst_file_src_get_property;
g_object_class_install_property (gobject_class, ARG_FD,
g_object_class_install_property (gobject_class, PROP_FD,
g_param_spec_int ("fd", "File-descriptor",
"File-descriptor for the file being mmap()d", 0, G_MAXINT, 0,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
g_object_class_install_property (gobject_class, ARG_LOCATION,
g_object_class_install_property (gobject_class, PROP_LOCATION,
g_param_spec_string ("location", "File Location",
"Location of the file to read", NULL,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
GST_PARAM_MUTABLE_READY));
g_object_class_install_property (gobject_class, ARG_MMAPSIZE,
g_param_spec_ulong ("mmapsize", "mmap() Block Size",
"Size in bytes of mmap()d regions", 0, G_MAXULONG, DEFAULT_MMAPSIZE,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
GST_PARAM_MUTABLE_PLAYING));
g_object_class_install_property (gobject_class, ARG_TOUCH,
g_param_spec_boolean ("touch", "Touch mapped region read data",
"Touch mmapped data regions to force them to be read from disk",
DEFAULT_TOUCH,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
GST_PARAM_MUTABLE_PLAYING));
/**
* GstFileSrc:use-mmap
*
* Whether to use mmap(). Set to TRUE to force use of mmap() instead of
* read() for reading data.
*
* Use of mmap() is disabled by default since with mmap() there are a
* number of occasions where the process/application will be notified of
* read errors via a SIGBUS signal from the kernel, which will lead to
* the application being killed if not handled by the application. This
* is something that is difficult to work around for a library like
* GStreamer, hence use of mmap() is disabled by default. Said errors
* can occur for example when an external device (e.g. an external hard
* drive or a portable music player) are unplugged while in use, or when
* a CD/DVD medium cannot be be read because the medium is scratched or
* otherwise damaged.
*
**/
g_object_class_install_property (gobject_class, ARG_USEMMAP,
g_param_spec_boolean ("use-mmap", "Use mmap to read data",
"Whether to use mmap() instead of read()",
DEFAULT_USEMMAP, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
GST_PARAM_MUTABLE_READY));
g_object_class_install_property (gobject_class, ARG_SEQUENTIAL,
g_param_spec_boolean ("sequential", "Optimise for sequential mmap access",
"Whether to use madvise to hint to the kernel that access to "
"mmap pages will be sequential",
DEFAULT_SEQUENTIAL, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS |
GST_PARAM_MUTABLE_PLAYING));
gobject_class->finalize = gst_file_src_finalize;
@ -301,21 +209,10 @@ gst_file_src_class_init (GstFileSrcClass * klass)
static void
gst_file_src_init (GstFileSrc * src)
{
#ifdef HAVE_MMAP
src->pagesize = getpagesize ();
#endif
src->filename = NULL;
src->fd = 0;
src->uri = NULL;
src->touch = DEFAULT_TOUCH;
src->mapbuf = NULL;
src->mapsize = DEFAULT_MMAPSIZE; /* default is 4MB */
src->use_mmap = DEFAULT_USEMMAP;
src->sequential = DEFAULT_SEQUENTIAL;
src->is_regular = FALSE;
}
@ -385,27 +282,9 @@ gst_file_src_set_property (GObject * object, guint prop_id,
src = GST_FILE_SRC (object);
switch (prop_id) {
case ARG_LOCATION:
case PROP_LOCATION:
gst_file_src_set_location (src, g_value_get_string (value));
break;
case ARG_MMAPSIZE:
if ((src->mapsize % src->pagesize) == 0) {
src->mapsize = g_value_get_ulong (value);
} else {
GST_INFO_OBJECT (src,
"invalid mapsize, must be a multiple of pagesize, which is %d",
src->pagesize);
}
break;
case ARG_TOUCH:
src->touch = g_value_get_boolean (value);
break;
case ARG_SEQUENTIAL:
src->sequential = g_value_get_boolean (value);
break;
case ARG_USEMMAP:
src->use_mmap = g_value_get_boolean (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
@ -423,352 +302,18 @@ gst_file_src_get_property (GObject * object, guint prop_id, GValue * value,
src = GST_FILE_SRC (object);
switch (prop_id) {
case ARG_LOCATION:
case PROP_LOCATION:
g_value_set_string (value, src->filename);
break;
case ARG_FD:
case PROP_FD:
g_value_set_int (value, src->fd);
break;
case ARG_MMAPSIZE:
g_value_set_ulong (value, src->mapsize);
break;
case ARG_TOUCH:
g_value_set_boolean (value, src->touch);
break;
case ARG_SEQUENTIAL:
g_value_set_boolean (value, src->sequential);
break;
case ARG_USEMMAP:
g_value_set_boolean (value, src->use_mmap);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
#undef HAVE_MMAP
/***
* mmap code below
*/
#ifdef HAVE_MMAP
/* GstMmapBuffer */
typedef struct _GstMmapBuffer GstMmapBuffer;
typedef struct _GstMmapBufferClass GstMmapBufferClass;
#define GST_TYPE_MMAP_BUFFER (gst_mmap_buffer_get_type())
#define GST_IS_MMAP_BUFFER(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_MMAP_BUFFER))
#define GST_IS_MMAP_BUFFER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_MMAP_BUFFER))
#define GST_MMAP_BUFFER_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_MMAP_BUFFER, GstMmapBufferClass))
#define GST_MMAP_BUFFER(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_MMAP_BUFFER, GstMmapBuffer))
#define GST_MMAP_BUFFER_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_MMAP_BUFFER, GstMmapBufferClass))
struct _GstMmapBuffer
{
GstBuffer buffer;
GstFileSrc *filesrc;
};
struct _GstMmapBufferClass
{
GstBufferClass buffer_class;
};
static void gst_mmap_buffer_finalize (GstMmapBuffer * mmap_buffer);
GType gst_mmap_buffer_get_type (void);
G_DEFINE_TYPE (GstMmapBuffer, gst_mmap_buffer, GST_TYPE_BUFFER);
static void
gst_mmap_buffer_class_init (GstMmapBufferClass * g_class)
{
GstMiniObjectClass *mini_object_class = GST_MINI_OBJECT_CLASS (g_class);
mini_object_class->finalize =
(GstMiniObjectFinalizeFunction) gst_mmap_buffer_finalize;
}
static void
gst_mmap_buffer_init (GstMmapBuffer * buf)
{
GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_READONLY);
/* before we re-enable this flag, we probably need to fix _copy()
* _make_writable(), etc. in GstMiniObject/GstBuffer as well */
/* GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_ORIGINAL); */
}
static void
gst_mmap_buffer_finalize (GstMmapBuffer * mmap_buffer)
{
guint size;
gpointer data;
guint64 offset;
GstFileSrc *src;
GstBuffer *buffer = GST_BUFFER (mmap_buffer);
/* get info */
size = GST_BUFFER_SIZE (buffer);
offset = GST_BUFFER_OFFSET (buffer);
data = GST_BUFFER_DATA (buffer);
src = mmap_buffer->filesrc;
GST_LOG ("freeing mmap()d buffer at %" G_GUINT64_FORMAT "+%u", offset, size);
#ifdef MADV_DONTNEED
/* madvise to tell the kernel what to do with it */
if (madvise (data, size, MADV_DONTNEED) < 0) {
GST_WARNING_OBJECT (src, "warning: madvise failed: %s", g_strerror (errno));
}
#endif
/* now unmap the memory */
if (munmap (data, size) < 0) {
GST_WARNING_OBJECT (src, "warning: munmap failed: %s", g_strerror (errno));
}
/* cast to unsigned long, since there's no gportable way to print
* guint64 as hex */
GST_LOG ("unmapped region %08lx+%08lx at %p",
(gulong) offset, (gulong) size, data);
GST_MINI_OBJECT_CLASS (gst_mmap_buffer_parent_class)->finalize
(GST_MINI_OBJECT (mmap_buffer));
}
static GstBuffer *
gst_file_src_map_region (GstFileSrc * src, off_t offset, gsize size,
gboolean testonly)
{
GstBuffer *buf;
void *mmapregion;
g_return_val_if_fail (offset >= 0, NULL);
/* FIXME ? use goffset and friends if we require glib >= 2.20 */
GST_LOG_OBJECT (src, "mapping region %08" G_GINT64_MODIFIER "x+%08lx "
"from file into memory", (gint64) offset, (gulong) size);
mmapregion = mmap (NULL, size, PROT_READ, MAP_SHARED, src->fd, offset);
if (mmapregion == NULL || mmapregion == MAP_FAILED)
goto mmap_failed;
GST_LOG_OBJECT (src, "mapped region %08lx+%08lx from file into memory at %p",
(gulong) offset, (gulong) size, mmapregion);
/* time to allocate a new mapbuf */
buf = (GstBuffer *) gst_mini_object_new (GST_TYPE_MMAP_BUFFER);
/* mmap() the data into this new buffer */
GST_BUFFER_DATA (buf) = mmapregion;
GST_MMAP_BUFFER (buf)->filesrc = src;
#ifdef MADV_SEQUENTIAL
if (src->sequential) {
/* madvise to tell the kernel what to do with it */
if (madvise (mmapregion, size, MADV_SEQUENTIAL) < 0) {
GST_WARNING_OBJECT (src, "warning: madvise failed: %s",
g_strerror (errno));
}
}
#endif
/* fill in the rest of the fields */
GST_BUFFER_SIZE (buf) = size;
GST_BUFFER_OFFSET (buf) = offset;
GST_BUFFER_OFFSET_END (buf) = offset + size;
GST_BUFFER_TIMESTAMP (buf) = GST_CLOCK_TIME_NONE;
return buf;
/* ERROR */
mmap_failed:
{
if (!testonly) {
GST_ELEMENT_ERROR (src, RESOURCE, READ, (NULL),
("mmap (0x%08lx, %d, 0x%" G_GINT64_MODIFIER "x) failed: %s",
(gulong) size, src->fd, (guint64) offset, g_strerror (errno)));
}
return NULL;
}
}
static GstBuffer *
gst_file_src_map_small_region (GstFileSrc * src, off_t offset, gsize size)
{
GstBuffer *ret;
off_t mod;
guint pagesize;
GST_LOG_OBJECT (src,
"attempting to map a small buffer at %" G_GUINT64_FORMAT "+%d",
(guint64) offset, (gint) size);
pagesize = src->pagesize;
mod = offset % pagesize;
/* if the offset starts at a non-page boundary, we have to special case */
if (mod != 0) {
gsize mapsize;
off_t mapbase;
GstBuffer *map;
mapbase = offset - mod;
mapsize = ((size + mod + pagesize - 1) / pagesize) * pagesize;
GST_LOG_OBJECT (src,
"not on page boundaries, resizing to map to %" G_GUINT64_FORMAT "+%d",
(guint64) mapbase, (gint) mapsize);
map = gst_file_src_map_region (src, mapbase, mapsize, FALSE);
if (map == NULL)
return NULL;
ret = gst_buffer_create_sub (map, offset - mapbase, size);
GST_BUFFER_OFFSET (ret) = GST_BUFFER_OFFSET (map) + offset - mapbase;
gst_buffer_unref (map);
} else {
ret = gst_file_src_map_region (src, offset, size, FALSE);
}
return ret;
}
static GstFlowReturn
gst_file_src_create_mmap (GstFileSrc * src, guint64 offset, guint length,
GstBuffer ** buffer)
{
GstBuffer *buf = NULL;
gsize readsize, mapsize;
off_t readend, mapstart, mapend;
int i;
/* calculate end pointers so we don't have to do so repeatedly later */
readsize = length;
readend = offset + readsize; /* note this is the byte *after* the read */
mapstart = GST_BUFFER_OFFSET (src->mapbuf);
mapsize = GST_BUFFER_SIZE (src->mapbuf);
mapend = mapstart + mapsize; /* note this is the byte *after* the map */
GST_LOG ("attempting to read %08lx, %08lx, %08lx, %08lx",
(unsigned long) readsize, (unsigned long) readend,
(unsigned long) mapstart, (unsigned long) mapend);
/* if the start is past the mapstart */
if (offset >= mapstart) {
/* if the end is before the mapend, the buffer is in current mmap region... */
/* ('cause by definition if readend is in the buffer, so's readstart) */
if (readend <= mapend) {
GST_LOG_OBJECT (src, "read buf %" G_GUINT64_FORMAT "+%u lives in "
"current mapbuf %u+%u, creating subbuffer of mapbuf",
offset, (guint) readsize, (guint) mapstart, (guint) mapsize);
buf = gst_buffer_create_sub (src->mapbuf, offset - mapstart, readsize);
GST_BUFFER_OFFSET (buf) = offset;
/* if the start actually is within the current mmap region, map an overlap buffer */
} else if (offset < mapend) {
GST_LOG_OBJECT (src, "read buf %" G_GUINT64_FORMAT "+%u starts in "
"mapbuf %u+%u but ends outside, creating new mmap",
offset, (guint) readsize, (guint) mapstart, (guint) mapsize);
buf = gst_file_src_map_small_region (src, offset, readsize);
if (buf == NULL)
goto could_not_mmap;
}
/* the only other option is that buffer is totally outside, which means we search for it */
/* now we can assume that the start is *before* the current mmap region */
/* if the readend is past mapstart, we have two options */
} else if (readend >= mapstart) {
/* either the read buffer overlaps the start of the mmap region */
/* or the read buffer fully contains the current mmap region */
/* either way, it's really not relevant, we just create a new region anyway */
GST_LOG_OBJECT (src, "read buf %" G_GUINT64_FORMAT "+%d starts before "
"mapbuf %d+%d, but overlaps it", (guint64) offset, (gint) readsize,
(gint) mapstart, (gint) mapsize);
buf = gst_file_src_map_small_region (src, offset, readsize);
if (buf == NULL)
goto could_not_mmap;
}
/* then deal with the case where the read buffer is totally outside */
if (buf == NULL) {
/* first check to see if there's a map that covers the right region already */
GST_LOG_OBJECT (src, "searching for mapbuf to cover %" G_GUINT64_FORMAT
"+%d", offset, (int) readsize);
/* if the read buffer crosses a mmap region boundary, create a one-off region */
if ((offset / src->mapsize) != (readend / src->mapsize)) {
GST_LOG_OBJECT (src, "read buf %" G_GUINT64_FORMAT "+%d crosses a "
"%d-byte boundary, creating a one-off", offset, (int) readsize,
(int) src->mapsize);
buf = gst_file_src_map_small_region (src, offset, readsize);
if (buf == NULL)
goto could_not_mmap;
/* otherwise we will create a new mmap region and set it to the default */
} else {
gsize mapsize;
off_t nextmap = offset - (offset % src->mapsize);
GST_LOG_OBJECT (src, "read buf %" G_GUINT64_FORMAT "+%d in new mapbuf "
"at %" G_GUINT64_FORMAT "+%d, mapping and subbuffering",
offset, (gint) readsize, (guint64) nextmap, (gint) src->mapsize);
/* first, we're done with the old mapbuf */
gst_buffer_unref (src->mapbuf);
mapsize = src->mapsize;
/* double the mapsize as long as the readsize is smaller */
while (readsize + offset > nextmap + mapsize) {
GST_LOG_OBJECT (src, "readsize smaller then mapsize %08x %d",
(guint) readsize, (gint) mapsize);
mapsize <<= 1;
}
/* create a new one */
src->mapbuf = gst_file_src_map_region (src, nextmap, mapsize, FALSE);
if (src->mapbuf == NULL)
goto could_not_mmap;
/* subbuffer it */
buf = gst_buffer_create_sub (src->mapbuf, offset - nextmap, readsize);
GST_BUFFER_OFFSET (buf) =
GST_BUFFER_OFFSET (src->mapbuf) + offset - nextmap;
}
}
/* if we need to touch the buffer (to bring it into memory), do so */
if (src->touch) {
volatile guchar *p = GST_BUFFER_DATA (buf);
/* read first byte of each page */
for (i = 0; i < GST_BUFFER_SIZE (buf); i += src->pagesize)
(void) p[i];
}
/* we're done, return the buffer */
*buffer = buf;
return GST_FLOW_OK;
/* ERROR */
could_not_mmap:
{
return GST_FLOW_ERROR;
}
}
#endif
/***
* read code below
* that is to say, you shouldn't read the code below, but the code that reads
@ -779,7 +324,6 @@ could_not_mmap:
* the sort of attitude we want to be advertising. No sir.
*
*/
static GstFlowReturn
gst_file_src_create_read (GstFileSrc * src, guint64 offset, guint length,
GstBuffer ** buffer)
@ -879,15 +423,7 @@ gst_file_src_create (GstBaseSrc * basesrc, guint64 offset, guint length,
src = GST_FILE_SRC_CAST (basesrc);
#ifdef HAVE_MMAP
if (src->using_mmap) {
ret = gst_file_src_create_mmap (src, offset, length, buffer);
} else {
ret = gst_file_src_create_read (src, offset, length, buffer);
}
#else
ret = gst_file_src_create_read (src, offset, length, buffer);
#endif
return ret;
}
@ -978,29 +514,14 @@ gst_file_src_start (GstBaseSrc * basesrc)
if (S_ISSOCK (stat_results.st_mode))
goto was_socket;
src->using_mmap = FALSE;
src->read_position = 0;
/* record if it's a regular (hence seekable and lengthable) file */
if (S_ISREG (stat_results.st_mode))
src->is_regular = TRUE;
#ifdef HAVE_MMAP
if (src->use_mmap) {
/* FIXME: maybe we should only try to mmap if it's a regular file */
/* allocate the first mmap'd region if it's a regular file ? */
src->mapbuf = gst_file_src_map_region (src, 0, src->mapsize, TRUE);
if (src->mapbuf != NULL) {
GST_DEBUG_OBJECT (src, "using mmap for file");
src->using_mmap = TRUE;
src->seekable = TRUE;
}
}
if (src->mapbuf == NULL)
#endif
/* We need to check if the underlying file is seekable. */
{
/* If not in mmap mode, we need to check if the underlying file is
* seekable. */
off_t res = lseek (src->fd, 0, SEEK_END);
if (res < 0) {
@ -1077,11 +598,6 @@ gst_file_src_stop (GstBaseSrc * basesrc)
src->fd = 0;
src->is_regular = FALSE;
if (src->mapbuf) {
gst_buffer_unref (src->mapbuf);
src->mapbuf = NULL;
}
return TRUE;
}

9
plugins/elements/gstfilesrc.h
View file

@ -55,23 +55,14 @@ struct _GstFileSrc {
GstBaseSrc element;
/*< private >*/
guint pagesize; /* system page size */
gchar *filename; /* filename */
gchar *uri; /* caching the URI */
gint fd; /* open file descriptor */
guint64 read_position; /* position of fd */
gboolean touch; /* whether to touch every page */
gboolean using_mmap; /* whether we opened it with mmap */
gboolean sequential; /* Whether to madvise (MADV_SEQUENTIAL)
for mmap pages */
gboolean seekable; /* whether the file is seekable */
gboolean is_regular; /* whether it's a (symlink to a)
regular file */
GstBuffer *mapbuf;
size_t mapsize;
gboolean use_mmap;
};
struct _GstFileSrcClass {