LockingSyncContext.java

package io.takari.aether.concurrency;

/*******************************************************************************
 * Copyright (c) 2010-2014 Takari, Inc., Sonatype, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *******************************************************************************/

import io.takari.filemanager.FileManager;
import io.takari.filemanager.Lock;

import java.io.File;
import java.io.IOException;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.TreeSet;

import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.SyncContext;
import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.metadata.Metadata;
import org.eclipse.aether.repository.LocalRepositoryManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class LockingSyncContext implements SyncContext {
  private static final char SEPARATOR = '~';
  
  private Logger logger = LoggerFactory.getLogger(LockingFileProcessor.class);  
  
  private final FileManager fileLockManager;
  private final LocalRepositoryManager localRepoMan;
  private final boolean shared;
  private final Map<String, Lock> locks = new LinkedHashMap<String, Lock>();

  public LockingSyncContext(boolean shared, RepositorySystemSession session, FileManager fileLockManager, Logger logger) {
    this.shared = shared;
    this.logger = logger;
    this.fileLockManager = fileLockManager;
    this.localRepoMan = session.getLocalRepositoryManager();        
  }

  public void acquire(Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas) {
    Collection<String> paths = new TreeSet<String>();
    addArtifactPaths(paths, artifacts);
    addMetadataPaths(paths, metadatas);
    File basedir = getLockBasedir();
    for (String path : paths) {
      File file = new File(basedir, path);
      Lock lock = locks.get(path);
      if (lock == null) {
        if (shared) {
          lock = fileLockManager.readLock(file);
        } else {
          lock = fileLockManager.writeLock(file);
        }
        locks.put(path, lock);
        try {
          lock.lock();
        } catch (IOException e) {
          logger.warn("Failed to lock file " + lock.getFile() + ": " + e);
        }
      }
    }
  }

  private File getLockBasedir() {
    return new File(localRepoMan.getRepository().getBasedir(), ".locks");
  }

  private void addArtifactPaths(Collection<String> paths, Collection<? extends Artifact> artifacts) {
    if (artifacts != null) {
      for (Artifact artifact : artifacts) {
        String path = getPath(artifact);
        paths.add(path);
      }
    }
  }

  private String getPath(Artifact artifact) {
    // NOTE: Don't use LRM.getPath*() as those paths could be different across processes, e.g. due to staging LRMs.
    StringBuilder path = new StringBuilder(128);
    path.append(artifact.getGroupId()).append(SEPARATOR);
    path.append(artifact.getArtifactId()).append(SEPARATOR);
    path.append(artifact.getBaseVersion());
    return path.toString();
  }

  private void addMetadataPaths(Collection<String> paths, Collection<? extends Metadata> metadatas) {
    if (metadatas != null) {
      for (Metadata metadata : metadatas) {
        String path = getPath(metadata);
        paths.add(path);
      }
    }
  }

  private String getPath(Metadata metadata) {
    // NOTE: Don't use LRM.getPath*() as those paths could be different across processes, e.g. due to staging.
    StringBuilder path = new StringBuilder(128);
    if (metadata.getGroupId().length() > 0) {
      path.append(metadata.getGroupId());
      if (metadata.getArtifactId().length() > 0) {
        path.append(SEPARATOR).append(metadata.getArtifactId());
        if (metadata.getVersion().length() > 0) {
          path.append(SEPARATOR).append(metadata.getVersion());
        }
      }
    }
    return path.toString();
  }

  public void close() {
    for (Lock lock : locks.values()) {
      try {
        lock.unlock();
      } catch (IOException e) {
        logger.warn("Failed to unlock file " + lock.getFile() + ": " + e);
      }
    }
    locks.clear();
  }
}