fs_fs.c

subversion-1.4.3-1.tar.gz 配置svn的源码

/* fs_fs.c --- filesystem operations specific to fs_fs
 *
 * ====================================================================
 * Copyright (c) 2000-2006 CollabNet.  All rights reserved.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution.  The terms
 * are also available at http://subversion.tigris.org/license-1.html.
 * If newer versions of this license are posted there, you may use a
 * newer version instead, at your option.
 *
 * This software consists of voluntary contributions made by many
 * individuals.  For exact contribution history, see the revision
 * history and logs, available at http://subversion.tigris.org/.
 * ====================================================================
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

#include <apr_general.h>
#include <apr_pools.h>
#include <apr_file_io.h>
#include <apr_uuid.h>
#include <apr_md5.h>
#include <apr_thread_mutex.h>

#include "svn_pools.h"
#include "svn_fs.h"
#include "svn_path.h"
#include "svn_hash.h"
#include "svn_md5.h"
#include "svn_sorts.h"
#include "svn_time.h"

#include "fs.h"
#include "err.h"
#include "tree.h"
#include "lock.h"
#include "revs-txns.h"
#include "key-gen.h"
#include "fs_fs.h"
#include "id.h"

#include "../libsvn_fs/fs-loader.h"

#include "svn_private_config.h"

/* Following are defines that specify the textual elements of the
   native filesystem directories and revision files. */

/* Names of special files in the fs_fs filesystem. */
#define PATH_FORMAT        "format"        /* Contains format number */
#define PATH_UUID          "uuid"          /* Contains UUID */
#define PATH_CURRENT       "current"       /* Youngest revision */
#define PATH_LOCK_FILE     "write-lock"    /* Revision lock file */
#define PATH_REVS_DIR      "revs"          /* Directory of revisions */
#define PATH_REVPROPS_DIR  "revprops"      /* Directory of revprops */
#define PATH_TXNS_DIR      "transactions"  /* Directory of transactions */
#define PATH_LOCKS_DIR     "locks"         /* Directory of locks */

/* Names of special files and file extensions for transactions */
#define PATH_CHANGES       "changes"       /* Records changes made so far */
#define PATH_TXN_PROPS     "props"         /* Transaction properties */
#define PATH_NEXT_IDS      "next-ids"      /* Next temporary ID assignments */
#define PATH_REV           "rev"           /* Proto rev file */
#define PATH_REV_LOCK      "rev-lock"      /* Proto rev (write) lock file */
#define PATH_PREFIX_NODE   "node."         /* Prefix for node filename */
#define PATH_EXT_TXN       ".txn"          /* Extension of txn dir */
#define PATH_EXT_CHILDREN  ".children"     /* Extension for dir contents */
#define PATH_EXT_PROPS     ".props"        /* Extension for node props */

/* Headers used to describe node-revision in the revision file. */
#define HEADER_ID          "id"
#define HEADER_TYPE        "type"
#define HEADER_COUNT       "count"
#define HEADER_PROPS       "props"
#define HEADER_TEXT        "text"
#define HEADER_CPATH       "cpath"
#define HEADER_PRED        "pred"
#define HEADER_COPYFROM    "copyfrom"
#define HEADER_COPYROOT    "copyroot"

/* Kinds that a change can be. */
#define ACTION_MODIFY      "modify"
#define ACTION_ADD         "add"
#define ACTION_DELETE      "delete"
#define ACTION_REPLACE     "replace"
#define ACTION_RESET       "reset"

/* True and False flags. */
#define FLAG_TRUE          "true"
#define FLAG_FALSE         "false"

/* Kinds that a node-rev can be. */
#define KIND_FILE          "file"
#define KIND_DIR           "dir"

/* Kinds of representation. */
#define REP_PLAIN          "PLAIN"
#define REP_DELTA          "DELTA"

/* Notes:

To avoid opening and closing the rev-files all the time, it would
probably be advantageous to keep each rev-file open for the
lifetime of the transaction object.  I'll leave that as a later
optimization for now.

I didn't keep track of pool lifetimes at all in this code.  There
are likely some errors because of that.
   
*/

/* The vtable associated with an open transaction object. */
static txn_vtable_t txn_vtable = {
  svn_fs_fs__commit_txn,
  svn_fs_fs__abort_txn,
  svn_fs_fs__txn_prop,
  svn_fs_fs__txn_proplist,
  svn_fs_fs__change_txn_prop,
  svn_fs_fs__txn_root
};

/* Pathname helper functions */

static const char *
path_format(svn_fs_t *fs, apr_pool_t *pool)
{
  return svn_path_join(fs->path, PATH_FORMAT, pool);
}

static const char *
path_uuid(svn_fs_t *fs, apr_pool_t *pool)
{
  return svn_path_join(fs->path, PATH_UUID, pool);
}

static const char *
path_current(svn_fs_t *fs, apr_pool_t *pool)
{
  return svn_path_join(fs->path, PATH_CURRENT, pool);
}

static const char *
path_lock(svn_fs_t *fs, apr_pool_t *pool)
{
  return svn_path_join(fs->path, PATH_LOCK_FILE, pool);
}

const char *
svn_fs_fs__path_rev(svn_fs_t *fs, svn_revnum_t rev, apr_pool_t *pool)
{
  return svn_path_join_many(pool, fs->path, PATH_REVS_DIR,
                            apr_psprintf(pool, "%ld", rev), NULL);
}

static const char *
path_revprops(svn_fs_t *fs, svn_revnum_t rev, apr_pool_t *pool)
{
  return svn_path_join_many(pool, fs->path, PATH_REVPROPS_DIR,
                            apr_psprintf(pool, "%ld", rev), NULL);
}

static const char *
path_txn_dir(svn_fs_t *fs, const char *txn_id, apr_pool_t *pool)
{
  return svn_path_join_many(pool, fs->path, PATH_TXNS_DIR,
                            apr_pstrcat(pool, txn_id, PATH_EXT_TXN, NULL),
                            NULL);
}

static const char *
path_txn_changes(svn_fs_t *fs, const char *txn_id, apr_pool_t *pool)
{
  return svn_path_join(path_txn_dir(fs, txn_id, pool), PATH_CHANGES, pool);
}

static const char *
path_txn_props(svn_fs_t *fs, const char *txn_id, apr_pool_t *pool)
{
  return svn_path_join(path_txn_dir(fs, txn_id, pool), PATH_TXN_PROPS, pool);
}

static const char *
path_txn_next_ids(svn_fs_t *fs, const char *txn_id, apr_pool_t *pool)
{
  return svn_path_join(path_txn_dir(fs, txn_id, pool), PATH_NEXT_IDS, pool);
}

static const char *
path_txn_proto_rev(svn_fs_t *fs, const char *txn_id, apr_pool_t *pool)
{
  return svn_path_join(path_txn_dir(fs, txn_id, pool), PATH_REV, pool);
}

static const char *
path_txn_proto_rev_lock(svn_fs_t *fs, const char *txn_id, apr_pool_t *pool)
{
  return svn_path_join(path_txn_dir(fs, txn_id, pool), PATH_REV_LOCK, pool);
}

static const char *
path_txn_node_rev(svn_fs_t *fs, const svn_fs_id_t *id, apr_pool_t *pool)
{
  const char *txn_id = svn_fs_fs__id_txn_id(id);
  const char *node_id = svn_fs_fs__id_node_id(id);
  const char *copy_id = svn_fs_fs__id_copy_id(id);
  const char *name = apr_psprintf(pool, PATH_PREFIX_NODE "%s.%s",
                                  node_id, copy_id);

  return svn_path_join(path_txn_dir(fs, txn_id, pool), name, pool);
}

static const char *
path_txn_node_props(svn_fs_t *fs, const svn_fs_id_t *id, apr_pool_t *pool)
{
  return apr_pstrcat(pool, path_txn_node_rev(fs, id, pool), PATH_EXT_PROPS,
                     NULL);
}

static const char *
path_txn_node_children(svn_fs_t *fs, const svn_fs_id_t *id, apr_pool_t *pool)
{
  return apr_pstrcat(pool, path_txn_node_rev(fs, id, pool),
                     PATH_EXT_CHILDREN, NULL);
}



/* Functions for working with shared transaction data. */

/* Return the transaction object for transaction TXN_ID from the
   transaction list of filesystem FS (which must already be locked via the
   txn_list_lock mutex).  If the transaction does not exist in the list,
   then create a new transaction object and return it (if CREATE_NEW is
   true) or return NULL (otherwise). */
static fs_fs_shared_txn_data_t *
get_shared_txn(svn_fs_t *fs, const char *txn_id, svn_boolean_t create_new)
{
  fs_fs_data_t *ffd = fs->fsap_data;
  fs_fs_shared_data_t *ffsd = ffd->shared;
  fs_fs_shared_txn_data_t *txn;

  for (txn = ffsd->txns; txn; txn = txn->next)
    if (strcmp(txn->txn_id, txn_id) == 0)
      break;

  if (txn || !create_new)
    return txn;

  /* Use the transaction object from the (single-object) freelist,
     if one is available, or otherwise create a new object. */
  if (ffsd->free_txn)
    {
      txn = ffsd->free_txn;
      ffsd->free_txn = NULL;
    }
  else
    {
      apr_pool_t *subpool = svn_pool_create(ffsd->common_pool);
      txn = apr_palloc(subpool, sizeof(*txn));
      txn->pool = subpool;
    }

  assert(strlen(txn_id) < sizeof(txn->txn_id));
  strcpy(txn->txn_id, txn_id);
  txn->being_written = FALSE;

  /* Link this transaction into the head of the list.  We will typically
     be dealing with only one active transaction at a time, so it makes
     sense for searches through the transaction list to look at the
     newest transactions first.  */
  txn->next = ffsd->txns;
  ffsd->txns = txn;

  return txn;
}

/* Free the transaction object for transaction TXN_ID, and remove it
   from the transaction list of filesystem FS (which must already be
   locked via the txn_list_lock mutex).  Do nothing if the transaction
   does not exist. */
static void
free_shared_txn(svn_fs_t *fs, const char *txn_id)
{
  fs_fs_data_t *ffd = fs->fsap_data;
  fs_fs_shared_data_t *ffsd = ffd->shared;
  fs_fs_shared_txn_data_t *txn, *prev = NULL;

  for (txn = ffsd->txns; txn; prev = txn, txn = txn->next)
    if (strcmp(txn->txn_id, txn_id) == 0)
      break;

  if (!txn)
    return;

  if (prev)
    prev->next = txn->next;
  else
    ffsd->txns = txn->next;

  /* As we typically will be dealing with one transaction after another,
     we will maintain a single-object free list so that we can hopefully
     keep reusing the same transaction object. */
  if (!ffsd->free_txn)
    ffsd->free_txn = txn;
  else
    svn_pool_destroy(txn->pool);
}


/* Obtain a lock on the transaction list of filesystem FS, call BODY
   with FS, BATON, and POOL, and then unlock the transaction list.
   Return what BODY returned. */
static svn_error_t *
with_txnlist_lock(svn_fs_t *fs,
                  svn_error_t *(*body)(svn_fs_t *fs,
                                       void *baton,
                                       apr_pool_t *pool),
                  void *baton,
                  apr_pool_t *pool)
{
  svn_error_t *err;
#if APR_HAS_THREADS
  fs_fs_data_t *ffd = fs->fsap_data;
  fs_fs_shared_data_t *ffsd = ffd->shared;
  apr_status_t apr_err;

  apr_err = apr_thread_mutex_lock(ffsd->txn_list_lock);
  if (apr_err)
    return svn_error_wrap_apr(apr_err, _("Can't grab FSFS txn list mutex"));
#endif

  err = body(fs, baton, pool);

#if APR_HAS_THREADS
  apr_err = apr_thread_mutex_unlock(ffsd->txn_list_lock);
  if (apr_err && !err)
    return svn_error_wrap_apr(apr_err, _("Can't ungrab FSFS txn list mutex"));
#endif

  return err;
}

/* A structure used by unlock_proto_rev() and unlock_proto_rev_body(),
   which see. */
struct unlock_proto_rev_baton
{
  const char *txn_id;
  void *lockcookie;
};

/* Callback used in the implementation of unlock_proto_rev(). */
static svn_error_t *
unlock_proto_rev_body(svn_fs_t *fs, void *baton, apr_pool_t *pool)
{
  struct unlock_proto_rev_baton *b = baton;
  const char *txn_id = b->txn_id;
  apr_file_t *lockfile = b->lockcookie;
  fs_fs_shared_txn_data_t *txn = get_shared_txn(fs, txn_id, FALSE);
  apr_status_t apr_err;

  if (!txn)
    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
                             _("Can't unlock unknown transaction '%s'"),
                             txn_id);
  if (!txn->being_written)
    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
                             _("Can't unlock nonlocked transaction '%s'"),
                             txn_id);

  apr_err = apr_file_unlock(lockfile);
  if (apr_err)
    return svn_error_wrap_apr
      (apr_err,
       _("Can't unlock prototype revision lockfile for transaction '%s'"),
       txn_id);
  apr_err = apr_file_close(lockfile);
  if (apr_err)
    return svn_error_wrap_apr
      (apr_err,
       _("Can't close prototype revision lockfile for transaction '%s'"),
       txn_id);

  txn->being_written = FALSE;

  return SVN_NO_ERROR;
}

/* Unlock the prototype revision file for transaction TXN_ID in filesystem
   FS using cookie LOCKCOOKIE.  The original prototype revision file must
   have been closed _before_ calling this function.

   Perform temporary allocations in POOL. */
static svn_error_t *
unlock_proto_rev(svn_fs_t *fs, const char *txn_id, void *lockcookie,
                 apr_pool_t *pool)
{
  struct unlock_proto_rev_baton b;

  b.txn_id = txn_id;
  b.lockcookie = lockcookie;
  return with_txnlist_lock(fs, unlock_proto_rev_body, &b, pool);
}