gate.lib.interaction.process.Process4StringStream Maven / Gradle / Ivy

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A GATE plugin that provides many different machine learning algorithms for a wide range of NLP-related machine learning tasks like text classification, tagging, or chunking.
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package gate.lib.interaction.process;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.util.Arrays;
import java.util.List;
import org.apache.log4j.Logger;
import java.util.Map;
import org.apache.log4j.Level;
/**
 * Minimalist class for exchanging String lines
 * 
 * This just sends or retrieves arbitrary lines of String which could be 
 * JSON we already have or want to parse ourself, or anything else. 
 * 
 * Note: the string being sent over this connection in either direction should
 * NOT contain any newline character!
 * 
 * NOTE: at the moment, reading from the process can block forever, there is
 * no timeout! 
 */
public class Process4StringStream extends ProcessBase
{

  private static final Logger LOGGER = Logger.getLogger(Process4StringStream.class.getName());
  
  private final Object synchronizer = new Object();
  

  private Process4StringStream() {
  }
  
  BufferedReader ir;
  PrintStream ps;
  
  public static Process4StringStream create(File workingDirectory, Map env,  List command) {
    Process4StringStream ret = new Process4StringStream();    
    if(workingDirectory != null) ret.workingDir = workingDirectory;
    if(env != null) ret.envvars.putAll(env);
    ret.command.addAll(command);
    ret.updateCommand4OS(ret.command);
    ret.ensureProcess();
    return ret;
  }
  public static Process4StringStream create(File workingDirectory, Map env,  String... command) {
    Process4StringStream ret = new Process4StringStream();    
    if(workingDirectory != null) ret.workingDir = workingDirectory;
    if(env != null) ret.envvars.putAll(env);
    ret.command.addAll(Arrays.asList(command));    
    ret.updateCommand4OS(ret.command);
    ret.ensureProcess(); 
    return ret;
    
  }
  
  
  @Override
  public Object readObject() {
    try {
      synchronized(synchronizer) {
        String str = ir.readLine();
        //System.err.println("DEBUG: got line: "+str);
        return str;
      }
    } catch (IOException ex) {
      throw new RuntimeException("Problem when reading from stream",ex);
    }
  }
  
  
  /**
   * Send a message to the process.
   * @param object  object to send
   */
  public void writeObject(Object object) {
    try {
      synchronized(synchronizer) {
        String str = (String)object;
        ps.println(str);
        ps.flush();
      }
    } catch (Exception ex) {
      throw new RuntimeException("Problem when writing to output connection",ex);
    }
  }
  
  /**
   * Check if the external process is running.
   * @return flag 
   */
  @Override
  public boolean isAlive() {
    return !need2start();
  }
  
  ///////////////////////////////////////////////////////////////////
  
  

  @Override
  protected void setupInteraction() {
    try {
      //System.err.println("Setting up the Print Stream");
      ps = new PrintStream(process.getOutputStream());
      //ps.println("Hello from Process4ObjectStream v1.0");
    } catch (Exception ex) {
      throw new RuntimeException("Could not create output connection",ex);
    }
    try {
      //System.err.println("Setting up the input stream");
      InputStream pis = process.getInputStream();
      ir = new BufferedReader(new InputStreamReader(pis,"UTF-8"));
      try {
        //String ret = ir.readLine();
        //System.err.println("Got hello from process: "+ret);
      } catch (Exception ex) {
        throw new RuntimeException("Could not receive the other side's hello message");
      }
    } catch (IOException ex) {
      throw new RuntimeException("Could not create input connection",ex);      
    }
    logStream(process.getErrorStream(), System.out);
    //System.err.println("DONE setting up the interaction");
  }

  @Override
  protected void stopInteraction() {
    try {
      ir.close();
    } catch (IOException ex) {
      //ignore
    }
    try {
      ps.close();
    } catch (Exception ex) {
      //ignore
    }
  }
  
  ////////////////////////////////////////////////
  
  public static void main(String[] args) {
    System.err.println("Running the Process4StringStream class");
    Process4StringStream pr = Process4StringStream.create(new File("."),null,"java -cp target/interaction-1.0-SNAPSHOT.jar:target/dependency/* gate.lib.interaction.process.EchoStream");
    //String someString = "this is some string";
    System.err.println("Right before writing to process");
    pr.writeObject("First line sent over");
    System.err.println("Right before reading from process");
    String ret = (String)pr.readObject();
    System.err.println("Got the line back: "+ret);
    System.err.println("Writing another one (1234)");
    pr.writeObject("1234");
    System.err.println("Right before reading again");
    ret = (String)pr.readObject();
    System.err.println("Got "+ret);
    System.err.println("Shutting down");
    pr.stop();
  }
  
}