PrepareCommit() приватный Метод

Call this to start a commit. this writes the new segments file, but writes an invalid checksum at the end, so that it is not visible to readers. Once this is called you must call #finishCommit to complete the commit or #rollbackCommit to abort it.

Note: #changed() should be called prior to this method if changes have been made to this SegmentInfos instance

private PrepareCommit ( Directory dir ) : void
dir Directory
Результат void
Документация по классу SegmentInfos
Пример #1
0
        /// <summary>
        /// Walk through all files referenced by the current
        ///  segmentInfos and ask the Directory to sync each file,
        ///  if it wasn't already.  If that succeeds, then we
        ///  prepare a new segments_N file but do not fully commit
        ///  it.
        /// </summary>
        private void StartCommit(SegmentInfos toSync)
        {
            Debug.Assert(TestPoint("startStartCommit"));
            Debug.Assert(PendingCommit == null);

            if (HitOOM)
            {
                throw new InvalidOperationException("this writer hit an OutOfMemoryError; cannot commit");
            }

            try
            {
                if (infoStream.IsEnabled("IW"))
                {
                    infoStream.Message("IW", "startCommit(): start");
                }

                lock (this)
                {
                    Debug.Assert(LastCommitChangeCount <= ChangeCount, "lastCommitChangeCount=" + LastCommitChangeCount + " changeCount=" + ChangeCount);

                    if (PendingCommitChangeCount == LastCommitChangeCount)
                    {
                        if (infoStream.IsEnabled("IW"))
                        {
                            infoStream.Message("IW", "  skip startCommit(): no changes pending");
                        }
                        Deleter.DecRef(FilesToCommit);
                        FilesToCommit = null;
                        return;
                    }

                    if (infoStream.IsEnabled("IW"))
                    {
                        infoStream.Message("IW", "startCommit index=" + SegString(ToLiveInfos(toSync).Segments) + " changeCount=" + ChangeCount);
                    }

                    Debug.Assert(FilesExist(toSync));
                }

                Debug.Assert(TestPoint("midStartCommit"));

                bool pendingCommitSet = false;

                try
                {
                    Debug.Assert(TestPoint("midStartCommit2"));

                    lock (this)
                    {
                        Debug.Assert(PendingCommit == null);

                        Debug.Assert(segmentInfos.Generation == toSync.Generation);

                        // Exception here means nothing is prepared
                        // (this method unwinds everything it did on
                        // an exception)
                        toSync.PrepareCommit(directory);
                        //System.out.println("DONE prepareCommit");

                        pendingCommitSet = true;
                        PendingCommit = toSync;
                    }

                    // this call can take a long time -- 10s of seconds
                    // or more.  We do it without syncing on this:
                    bool success = false;
                    ICollection<string> filesToSync;
                    try
                    {
                        filesToSync = toSync.Files(directory, false);
                        directory.Sync(filesToSync);
                        success = true;
                    }
                    finally
                    {
                        if (!success)
                        {
                            pendingCommitSet = false;
                            PendingCommit = null;
                            toSync.RollbackCommit(directory);
                        }
                    }

                    if (infoStream.IsEnabled("IW"))
                    {
                        infoStream.Message("IW", "done all syncs: " + filesToSync);
                    }

                    Debug.Assert(TestPoint("midStartCommitSuccess"));
                }
                finally
                {
                    lock (this)
                    {
                        // Have our master segmentInfos record the
                        // generations we just prepared.  We do this
                        // on error or success so we don't
                        // double-write a segments_N file.
                        segmentInfos.UpdateGeneration(toSync);

                        if (!pendingCommitSet)
                        {
                            if (infoStream.IsEnabled("IW"))
                            {
                                infoStream.Message("IW", "hit exception committing segments file");
                            }

                            // Hit exception
                            Deleter.DecRef(FilesToCommit);
                            FilesToCommit = null;
                        }
                    }
                }
            }
            catch (System.OutOfMemoryException oom)
            {
                HandleOOM(oom, "startCommit");
            }
            Debug.Assert(TestPoint("finishStartCommit"));
        }