content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.proxy;
  
  import alluxio.RestUtils;
  import alluxio.StreamCache;
  import alluxio.client.file.FileInStream;
  import alluxio.client.file.FileOutStream;
  import alluxio.conf.Configuration;
  import alluxio.web.ProxyWebServer;
  
  import com.google.common.io.ByteStreams;
  import io.swagger.annotations.Api;
  import io.swagger.annotations.ApiOperation;
  
  import java.io.InputStream;
  import javax.annotation.concurrent.NotThreadSafe;
  import javax.servlet.ServletContext;
  import javax.ws.rs.Consumes;
  import javax.ws.rs.POST;
  import javax.ws.rs.Path;
  import javax.ws.rs.PathParam;
  import javax.ws.rs.Produces;
  import javax.ws.rs.core.Context;
  import javax.ws.rs.core.MediaType;
  import javax.ws.rs.core.Response;
  
  /**
   * This class is a REST handler for stream resources.
   */
  @NotThreadSafe
  @Api(value = "/streams", description = "RESTful gateway for Alluxio Filesystem Client (Data)")
  @Path(StreamsRestServiceHandler.SERVICE_PREFIX)
  @Produces(MediaType.APPLICATION_JSON)
  @Consumes(MediaType.APPLICATION_JSON)
  public final class StreamsRestServiceHandler {
    public static final String SERVICE_PREFIX = "streams";
  
    public static final String ID_PARAM = "{id}/";
  
    public static final String CLOSE = "close";
    public static final String READ = "read";
    public static final String WRITE = "write";
  
    private final StreamCache mStreamCache;
  
    /**
     * Constructs a new {@link StreamsRestServiceHandler}.
     *
     * @param context context for the servlet
     */
    public StreamsRestServiceHandler(@Context ServletContext context) {
      mStreamCache =
          (StreamCache) context.getAttribute(ProxyWebServer.STREAM_CACHE_SERVLET_RESOURCE_KEY);
    }
  
    /**
     * @summary closes a stream
     * @param id the stream id
     * @return the response object
     */
    @POST
    @Path(ID_PARAM + CLOSE)
    @ApiOperation(value = "Closes the stream associated with the id", response = java.lang.Void.class)
    public Response close(@PathParam("id") final Integer id) {
      return RestUtils.call((RestUtils.RestCallable<Void>) () -> {
        // When a stream is invalidated from the cache, the removal listener of the cache will
        // automatically close the stream.
        if (mStreamCache.invalidate(id) == null) {
          throw new IllegalArgumentException("stream does not exist");
        }
        return null;
      }, Configuration.global());
    }
  
    /**
     * @summary reads from a stream
     * @param id the stream id
     * @return the response object
     */
    @POST
    @Path(ID_PARAM + READ)
    @ApiOperation(value = "Returns the input stream associated with the id",
        response = java.io.InputStream.class)
    @Produces(MediaType.APPLICATION_OCTET_STREAM)
    public Response read(@PathParam("id") final Integer id) {
      // TODO(jiri): Support reading a file range.
      return RestUtils.call(new RestUtils.RestCallable<InputStream>() {
        @Override
        public InputStream call() throws Exception {
          FileInStream is = mStreamCache.getInStream(id);
          if (is != null) {
            return is;
          }
          throw new IllegalArgumentException("stream does not exist");
        }
      }, Configuration.global());
    }
  
    /**
     * @summary writes to a stream
     * @param id the stream id
     * @param is the input stream
     * @return the response object
     */
    @POST
    @Path(ID_PARAM + WRITE)
    @ApiOperation(value = "Writes to the given output stream associated with the id",
        response = java.lang.Integer.class)
    @Consumes(MediaType.APPLICATION_OCTET_STREAM)
    public Response write(@PathParam("id") final Integer id, final InputStream is) {
      return RestUtils.call(() -> {
        FileOutStream os = mStreamCache.getOutStream(id);
        if (os != null) {
          return ByteStreams.copy(is, os);
        }
        throw new IllegalArgumentException("stream does not exist");
      }, Configuration.global());
    }
  }
  