From: Martin Mares <mj@ucw.cz>
Date: Sat, 9 Dec 2006 18:48:39 +0000 (+0100)
Subject: Added a direct I/O fastbuf backend.
X-Git-Tag: holmes-import~506^2~13^2~212
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=7b9f085a0cc79ca3263b1fdaff66119bd03a49f6;p=libucw.git

Added a direct I/O fastbuf backend.
---

diff --git a/lib/fastbuf.h b/lib/fastbuf.h
index 922798ff..c5e1deb8 100644
--- a/lib/fastbuf.h
+++ b/lib/fastbuf.h
@@ -97,6 +97,14 @@ struct fastbuf *fbmem_clone_read(struct fastbuf *);	/* Create reading fastbuf */
 
 struct fastbuf *bopen_mm(byte *name, uns mode);
 
+/* FastIO on files opened with O_DIRECT (see fb-direct.c for description) */
+
+struct asio_queue;
+struct fastbuf *fbdir_open(byte *name, uns mode, struct asio_queue *io_queue);
+struct fastbuf *fbdir_open_try(byte *name, uns mode, struct asio_queue *io_queue);
+struct fastbuf *fbdir_open_fd(int fd, struct asio_queue *io_queue);
+struct fastbuf *fbdir_open_tmp(int fd, struct asio_queue *io_queue);
+
 /* FastI on file descriptors with limit */
 
 struct fastbuf *bopen_limited_fd(int fd, uns bufsize, uns limit);
diff --git a/lib/fb-direct.c b/lib/fb-direct.c
new file mode 100644
index 00000000..e6254752
--- /dev/null
+++ b/lib/fb-direct.c
@@ -0,0 +1,389 @@
+/*
+ *	UCW Library -- Fast Buffered I/O on O_DIRECT Files
+ *
+ *	(c) 2006 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+/*
+ *	This is a fastbuf backend for fast streaming I/O using O_DIRECT and
+ *	the asynchronous I/O module. It's designed for use on large files
+ *	which don't fit in the disk cache.
+ *
+ *	CAVEATS:
+ *
+ *	  - All operations with a single fbdirect handle must be done
+ *	    within a single thread, unless you provide a custom I/O queue
+ *	    and take care of locking.
+ *
+ *	FIXME: what if the OS doesn't support O_DIRECT?
+ *	FIXME: doc: don't mix threads
+ *	FIXME: unaligned seeks and partial writes?
+ *	FIXME: merge with other file-oriented fastbufs
+ */
+
+#undef LOCAL_DEBUG
+
+#include "lib/lib.h"
+#include "lib/fastbuf.h"
+#include "lib/lfs.h"
+#include "lib/asio.h"
+#include "lib/conf.h"
+#include "lib/getopt.h"
+
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+
+static uns fbdir_cheat;
+static uns fbdir_buffer_size = 65536;
+static uns fbdir_read_ahead = 1;
+static uns fbdir_write_back = 1;
+
+static struct cf_section fbdir_cf = {
+  CF_ITEMS {
+    CF_UNS("Cheat", &fbdir_cheat),
+    CF_UNS("BufferSize", &fbdir_buffer_size),
+    CF_UNS("ReadAhead", &fbdir_read_ahead),
+    CF_UNS("WriteBack", &fbdir_write_back),
+    CF_END
+  }
+};
+
+#define FBDIR_ALIGN 512
+
+static pthread_key_t fbdir_queue_key;
+
+enum fbdir_mode {				// Current operating mode
+    M_NULL,
+    M_READ,
+    M_WRITE
+};
+
+struct fb_direct {
+  struct fastbuf fb;
+  int fd;					// File descriptor
+  int is_temp_file;				// 0=normal file, 1=temporary file, delete on close, -1=shared FD
+  struct asio_queue *io_queue;			// I/O queue to use
+  struct asio_queue *user_queue;		// If io_queue was supplied by the user
+  struct asio_request *pending_read;
+  struct asio_request *done_read;
+  struct asio_request *active_buffer;
+  enum fbdir_mode mode;
+  byte name[0];
+};
+#define FB_DIRECT(f) ((struct fb_direct *)(f)->is_fastbuf)
+
+static void CONSTRUCTOR
+fbdir_global_init(void)
+{
+  cf_declare_section("FBDirect", &fbdir_cf, 0);
+  if (pthread_key_create(&fbdir_queue_key, NULL) < 0)
+    die("Cannot create fbdir_queue_key: %m");
+}
+
+static void
+fbdir_read_sync(struct fb_direct *F)
+{
+  while (F->pending_read)
+    {
+      struct asio_request *r = asio_wait(F->io_queue);
+      ASSERT(r);
+      struct fb_direct *G = r->user_data;
+      ASSERT(G);
+      ASSERT(G->pending_read == r && !G->done_read);
+      G->pending_read = NULL;
+      G->done_read = r;
+    }
+}
+
+static void
+fbdir_change_mode(struct fb_direct *F, enum fbdir_mode mode)
+{
+  if (F->mode == mode)
+    return;
+  DBG("FB-DIRECT: Switching mode to %d", mode);
+  switch (F->mode)
+    {
+    case M_NULL:
+      break;
+    case M_READ:
+      fbdir_read_sync(F);			// Wait for read-ahead requests to finish
+      if (F->done_read)				// Return read-ahead requests if any
+	{
+	  asio_put(F->done_read);
+	  F->done_read = NULL;
+	}
+      break;
+    case M_WRITE:
+      asio_sync(F->io_queue);			// Wait for pending writebacks
+      break;
+    }
+  if (F->active_buffer)
+    {
+      asio_put(F->active_buffer);
+      F->active_buffer = NULL;
+    }
+  F->mode = mode;
+}
+
+static void
+fbdir_submit_read(struct fb_direct *F)
+{
+  struct asio_request *r = asio_get(F->io_queue);
+  r->fd = F->fd;
+  r->op = ASIO_READ;
+  r->len = F->io_queue->buffer_size;
+  r->user_data = F;
+  asio_submit(r);
+  F->pending_read = r;
+}
+
+static int
+fbdir_refill(struct fastbuf *f)
+{
+  struct fb_direct *F = FB_DIRECT(f);
+
+  DBG("FB-DIRECT: Refill");
+
+  if (!F->done_read)
+    {
+      if (!F->pending_read)
+	{
+	  fbdir_change_mode(F, M_READ);
+	  fbdir_submit_read(F);
+	}
+      fbdir_read_sync(F);
+      ASSERT(F->done_read);
+    }
+
+  struct asio_request *r = F->done_read;
+  F->done_read = NULL;
+  if (F->active_buffer)
+    asio_put(F->active_buffer);
+  F->active_buffer = r;
+  if (!r->status)
+    return 0;
+  if (r->status < 0)
+    die("Error reading %s: %s", f->name, strerror(r->returned_errno));
+  f->bptr = f->buffer = r->buffer;
+  f->bstop = f->bufend = f->buffer + r->status;
+  f->pos += r->status;
+
+  fbdir_submit_read(F);				// Read-ahead the next block
+
+  return r->status;
+}
+
+static void
+fbdir_spout(struct fastbuf *f)
+{
+  struct fb_direct *F = FB_DIRECT(f);
+  struct asio_request *r;
+
+  DBG("FB-DIRECT: Spout");
+
+  fbdir_change_mode(F, M_WRITE);
+  r = F->active_buffer;
+  if (r && f->bptr > f->bstop)
+    {
+      r->op = ASIO_WRITE_BACK;
+      r->fd = F->fd;
+      r->len = f->bptr - f->bstop;
+      ASSERT(!(f->pos % FBDIR_ALIGN) || fbdir_cheat);
+      f->pos += r->len;
+      if (!fbdir_cheat && r->len % FBDIR_ALIGN)			// Have to simulate incomplete writes
+	{
+	  r->len = ALIGN_TO(r->len, FBDIR_ALIGN);
+	  asio_submit(r);
+	  asio_sync(F->io_queue);
+	  DBG("FB-DIRECT: Truncating at %Ld", (long long)f->pos);
+	  if (sh_ftruncate(F->fd, f->pos) < 0)
+	    die("Error truncating %s: %m", f->name);
+	}
+      else
+	asio_submit(r);
+      r = NULL;
+    }
+  if (!r)
+    r = asio_get(F->io_queue);
+  f->bstop = f->bptr = f->buffer = r->buffer;
+  f->bufend = f->buffer + F->io_queue->buffer_size;
+  F->active_buffer = r;
+}
+
+static void
+fbdir_seek(struct fastbuf *f, sh_off_t pos, int whence)
+{
+  DBG("FB-DIRECT: Seek %Ld %d", (long long)pos, whence);
+
+  if (whence == SEEK_SET && pos == f->pos)
+    return;
+
+  fbdir_change_mode(FB_DIRECT(f), M_NULL);			// Wait for all async requests to finish
+  sh_off_t l = sh_seek(FB_DIRECT(f)->fd, pos, whence);
+  if (l < 0)
+    die("lseek on %s: %m", f->name);
+  f->pos = l;
+}
+
+static struct asio_queue *
+fbdir_get_io_queue(void)
+{
+  struct asio_queue *q = pthread_getspecific(fbdir_queue_key);
+  if (!q)
+    {
+      q = xmalloc_zero(sizeof(struct asio_queue));
+      q->buffer_size = fbdir_buffer_size;
+      q->max_writebacks = fbdir_write_back;
+      asio_init_queue(q);
+      pthread_setspecific(fbdir_queue_key, q);
+    }
+  q->use_count++;
+  DBG("FB-DIRECT: Got I/O queue, uc=%d", q->use_count);
+  return q;
+}
+
+static void
+fbdir_put_io_queue(void)
+{
+  struct asio_queue *q = pthread_getspecific(fbdir_queue_key);
+  ASSERT(q);
+  DBG("FB-DIRECT: Put I/O queue, uc=%d", q->use_count);
+  if (!--q->use_count)
+    {
+      asio_cleanup_queue(q);
+      xfree(q);
+      pthread_setspecific(fbdir_queue_key, NULL);
+    }
+}
+
+static void
+fbdir_close(struct fastbuf *f)
+{
+  struct fb_direct *F = FB_DIRECT(f);
+
+  DBG("FB-DIRECT: Close");
+
+  fbdir_change_mode(F, M_NULL);
+  if (!F->user_queue)
+    fbdir_put_io_queue();
+
+  switch (F->is_temp_file)
+    {
+    case 1:
+      if (unlink(f->name) < 0)
+	log(L_ERROR, "unlink(%s): %m", f->name);
+    case 0:
+      close(F->fd);
+    }
+
+  xfree(f);
+}
+
+static int
+fbdir_config(struct fastbuf *f, uns item, int value)
+{
+  switch (item)
+    {
+    case BCONFIG_IS_TEMP_FILE:
+      FB_DIRECT(f)->is_temp_file = value;
+      return 0;
+    default:
+      return -1;
+    }
+}
+
+static struct fastbuf *
+fbdir_open_internal(byte *name, int fd, struct asio_queue *q)
+{
+  int namelen = strlen(name) + 1;
+  struct fb_direct *F = xmalloc(sizeof(struct fb_direct) + namelen);
+  struct fastbuf *f = &F->fb;
+
+  DBG("FB-DIRECT: Open");
+  bzero(F, sizeof(*F));
+  f->name = F->name;
+  memcpy(f->name, name, namelen);
+  F->fd = fd;
+  if (q)
+    F->io_queue = F->user_queue = q;
+  else
+    F->io_queue = fbdir_get_io_queue();
+  f->refill = fbdir_refill;
+  f->spout = fbdir_spout;
+  f->seek = fbdir_seek;
+  f->close = fbdir_close;
+  f->config = fbdir_config;
+  f->can_overwrite_buffer = 2;
+  return f;
+}
+
+struct fastbuf *
+fbdirect_open_try(byte *name, uns mode, struct asio_queue *q)
+{
+  if (!fbdir_cheat)
+    mode |= O_DIRECT;
+  int fd = sh_open(name, mode, 0666);
+  if (fd < 0)
+    return NULL;
+  struct fastbuf *b = fbdir_open_internal(name, fd, q);
+  if (mode & O_APPEND)
+    fbdir_seek(b, 0, SEEK_END);
+  return b;
+}
+
+struct fastbuf *
+fbdirect_open(byte *name, uns mode, struct asio_queue *q)
+{
+  struct fastbuf *b = fbdirect_open_try(name, mode, q);
+  if (!b)
+    die("Unable to %s file %s: %m",
+	(mode & O_CREAT) ? "create" : "open", name);
+  return b;
+}
+
+struct fastbuf *
+fbdirect_open_fd(int fd, struct asio_queue *q)
+{
+  byte x[32];
+
+  sprintf(x, "fd%d", fd);
+  if (!fbdir_cheat && fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_DIRECT) < 0)
+    log(L_WARN, "Cannot set O_DIRECT on fd %d: %m", fd);
+  return fbdir_open_internal(x, fd, q);
+}
+
+#ifdef TEST
+
+int main(int argc, char **argv)
+{
+  struct fastbuf *f, *t;
+
+  log_init(NULL);
+  if (cf_getopt(argc, argv, CF_SHORT_OPTS, CF_NO_LONG_OPTS, NULL) >= 0)
+    die("Hey, whaddya want?");
+  f = (optind < argc) ? fbdirect_open(argv[optind++], O_RDONLY, NULL) : fbdirect_open_fd(0, NULL);
+  t = (optind < argc) ? fbdirect_open(argv[optind++], O_RDWR | O_CREAT | O_TRUNC, NULL) : fbdirect_open_fd(1, NULL);
+
+  bbcopy(f, t, ~0U);
+  ASSERT(btell(f) == btell(t));
+
+#if 0		// This triggers unaligned write
+  bflush(t);
+  bputc(t, '\n');
+#endif
+
+  brewind(t);
+  bgetc(t);
+  ASSERT(btell(t) == 1);
+
+  bclose(f);
+  bclose(t);
+  return 0;
+}
+
+#endif