Bug 303808: Add a GDB CLI Console history buffer

Change-Id: Ide52d3223b65323f3e9476d2c280d0ebe6640ba8

2 files changed, 335 insertions, 94 deletions

diff --git a/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbFullCliConsole.java b/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbFullCliConsole.java
index e1c0daf854c..252f0e3a4a8 100644
--- a/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbFullCliConsole.java
+++ b/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbFullCliConsole.java
@@ -7,23 +7,12 @@
  *******************************************************************************/
 package org.eclipse.cdt.dsf.gdb.internal.ui.console;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.util.HashSet;
-import java.util.Set;
-
 import org.eclipse.cdt.debug.ui.debuggerconsole.IDebuggerConsoleView;
 import org.eclipse.cdt.utils.pty.PTY;
 import org.eclipse.core.runtime.CoreException;
-import org.eclipse.core.runtime.IProgressMonitor;
-import org.eclipse.core.runtime.IStatus;
-import org.eclipse.core.runtime.Status;
-import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.debug.core.ILaunch;
 import org.eclipse.debug.core.ILaunchConfiguration;
 import org.eclipse.debug.ui.DebugUITools;
-import org.eclipse.tm.internal.terminal.provisional.api.ITerminalControl;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.console.AbstractConsole;
 import org.eclipse.ui.console.IConsoleView;
@@ -62,89 +51,6 @@ public class GdbFullCliConsole extends AbstractConsole implements IGDBDebuggerCo
 		super.dispose();
 	}
 
-	/**
-	 * This class will read from the GDB process output and error streams and will
-	 * write it to any registered ITerminalControl.
-	 * It must continue reading from the streams, even if there are no ITerminalControl
-	 * to write to.  This is important to prevent GDB's output buffer from getting full
-	 * and then completely stopping.
-	 */
-	private final class GdbTerminalConnector implements IGdbTerminalControlConnector {
-		private final Set<ITerminalControl> fTerminalPageControls = new HashSet<>();
-		private final Process fProcess;
-		private final Job fOutputStreamJob;
-		private final Job fErrorStreamJob;
-		
-		public GdbTerminalConnector(Process process) {
-			fProcess = process;
-			
-			fOutputStreamJob = new OutputReadJob(process.getInputStream());
-			fOutputStreamJob.schedule();
-			fErrorStreamJob = new OutputReadJob(process.getErrorStream());
-			fErrorStreamJob.schedule();
-		}
-
-		public void dispose() {
-			fOutputStreamJob.cancel();
-			fErrorStreamJob.cancel();
-		}
-		
-		@Override
-		public void addPageTerminalControl(ITerminalControl terminalControl) {
-			fTerminalPageControls.add(terminalControl);
-		}
-
-		@Override
-		public void removePageTerminalControl(ITerminalControl terminalControl) {
-			if (terminalControl != null) {
-				fTerminalPageControls.remove(terminalControl);
-			}
-		}
-
-		@Override
-		public OutputStream getTerminalToRemoteStream() {
-			// When the user writes to the terminal, it should be sent
-			// directly to GDB
-			return fProcess.getOutputStream();
-		}
-		
-		private class OutputReadJob extends Job {
-	    	{
-	    		setSystem(true); 
-	    	}
-	    	
-	    	private InputStream fInputStream;
-	    	
-	    	private OutputReadJob(InputStream inputStream) {
-	            super("GDB CLI output Job"); //$NON-NLS-1$
-	            fInputStream = inputStream;
-	        }
-
-	        @Override
-			protected IStatus run(IProgressMonitor monitor) {
-	            try {
-	                byte[] b = new byte[1024];
-	                int read = 0;
-	                do {
-	                	if (monitor.isCanceled()) {
-	                		break;
-	                	}
-	                	
-	                	read = fInputStream.read(b);
-	                	if (read > 0) {
-	                		for (ITerminalControl control : fTerminalPageControls) {
-		                		control.getRemoteToTerminalOutputStream().write(b, 0, read);	                			
-	                		}
-	                	}
-	                } while (read >= 0);
-	            } catch (IOException e) {
-	            }
-
-	            return Status.OK_STATUS;
-	        }
-	    }
-	}
-
 	@Override
 	public ILaunch getLaunch() { return fLaunch; }
     
diff --git a/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbTerminalConnector.java b/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbTerminalConnector.java
new file mode 100644
index 00000000000..119cac1f189
--- /dev/null
+++ b/dsf-gdb/org.eclipse.cdt.dsf.gdb.ui/src/org/eclipse/cdt/dsf/gdb/internal/ui/console/GdbTerminalConnector.java
@@ -0,0 +1,335 @@
+/*******************************************************************************
+ * Copyright (c) 2016 Ericsson and others.
+ * 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
+ *******************************************************************************/
+package org.eclipse.cdt.dsf.gdb.internal.ui.console;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayDeque;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.eclipse.cdt.dsf.gdb.IGdbDebugPreferenceConstants;
+import org.eclipse.cdt.dsf.gdb.internal.ui.GdbUIPlugin;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.Status;
+import org.eclipse.core.runtime.jobs.Job;
+import org.eclipse.jface.preference.IPreferenceStore;
+import org.eclipse.tm.internal.terminal.provisional.api.ITerminalControl;
+
+/**
+ * This class will read from the GDB process output and error streams and will write it to any registered
+ * ITerminalControl. It must continue reading from the streams, even if there are no ITerminalControl to write
+ * to. This is important to prevent GDB's output buffer from getting full and then completely stopping.
+ * 
+ * In addition this class manages a history buffer which will be used to populate a new console with history 
+ * information already collected for the same session. Used for example when closing an re-opening a console. 
+ */
+public class GdbTerminalConnector implements IGdbTerminalControlConnector {
+	/**
+	 * The maximum number of lines the internal history buffer can hold
+	 */
+	private static final int HIST_BUFFER_MAX_SIZE = 1000; /* lines */
+
+	/**
+	 * The History buffer is written out in chunks of lines, this chunks are taken from the total history buffer
+	 * and written out sequentially.
+	 * This constant determines the writing size in number of lines (i.e. chunk size)
+	 */
+	private static final int HIST_BUFFER_WRITE_SIZE = 100; /* lines */
+	private final Process fProcess;
+	private final Set<ITerminalControl> fTerminalPageControls = Collections.synchronizedSet(new HashSet<>());
+	private final Job fOutputStreamJob;
+	private final Job fErrorStreamJob;
+	private final ConsoleHistoryLinesBuffer fHistoryBuffer;
+
+	public GdbTerminalConnector(Process process) {
+		fProcess = process;
+
+		// Using a history buffer size aligned with the preferences for console buffering 
+		// but not exceeding the internal maximum
+		//   We cap the history buffer to an internal maximum in order to prevent excessive use 
+		// of memory, the preference value applies to the console (not the history buffer) and can be specified
+		// to billions of lines.
+		//   Handling billion of lines for the history buffer would require a completely different approach 
+		// to this implementation, possibly making use of the hard disk instead of in memory.
+		IPreferenceStore store = GdbUIPlugin.getDefault().getPreferenceStore();
+		int prefBufferLines = store.getInt(IGdbDebugPreferenceConstants.PREF_CONSOLE_BUFFERLINES);
+		int history_buffer_size = prefBufferLines < HIST_BUFFER_MAX_SIZE ? prefBufferLines
+				: HIST_BUFFER_MAX_SIZE;
+
+		fHistoryBuffer = new ConsoleHistoryLinesBuffer(history_buffer_size);
+		
+		// Start the jobs that read the GDB process output streams
+		String jobSuffix = ""; //$NON-NLS-1$
+		fOutputStreamJob = new OutputReadJob(process.getInputStream(), jobSuffix);
+		fOutputStreamJob.schedule();
+		
+		jobSuffix = "-Error"; //$NON-NLS-1$
+		fErrorStreamJob = new OutputReadJob(process.getErrorStream(), jobSuffix);
+		fErrorStreamJob.schedule();
+	}
+
+	/**
+	 * This class will hold a buffer of history lines, it uses a queue to easily pop out the oldest lines once
+	 * the maximum is being exceeded.</br>
+	 * It also keeps track of partial text at the end of the receiving input i.e. not yet forming a complete
+	 * line, once it forms a complete line it gets integrated in the queue
+	 * 
+	 * In addition the API used in this implementation are synchronized to allow consistent information among
+	 * the Jobs using it
+	 */
+	private class ConsoleHistoryLinesBuffer extends ArrayDeque<String> {
+
+		private static final long serialVersionUID = 1L;
+		/**
+		 * Holds the last characters received but not yet forming a complete line, The HistoryBuffer contains
+		 * complete lines to be able to keep a proper line count that can be then be dimensioned by e.g.
+		 * preferences
+		 */
+		private final StringBuilder fHistoryRemainder = new StringBuilder();
+
+		public ConsoleHistoryLinesBuffer(int size) {
+			super(size);
+		}
+
+		/**
+		 * A simple container holding consistent information of the history lines and accumulated remainder
+		 * at a particular point in time
+		 */
+		private class HistorySnapShot {
+			private final String[] fHistoryLinesSnapShot;
+			private final String	fHistoryRemainderSnapShot;
+			private HistorySnapShot(String[] historyLines, String historyRemainder) {
+				fHistoryLinesSnapShot = historyLines;
+				fHistoryRemainderSnapShot = historyRemainder;
+			}
+		}
+		
+		@Override
+		public synchronized int size() {
+			return super.size();
+		}
+
+		/**
+		 * @param text
+		 *            Accumulate the text not yet forming a line
+		 */
+		private synchronized void appendRemainder(String text) {
+			fHistoryRemainder.append(text);
+		}
+
+		/**
+		 * @return Returns the accumulated text and clears its internal value
+		 */
+		private synchronized String popRemainder() {
+			String remainder = fHistoryRemainder.toString();
+			fHistoryRemainder.setLength(0);
+			return remainder;
+		}
+
+		/**
+		 * @return The history information at a specific point in time
+		 */
+		private synchronized HistorySnapShot getHistorySnapShot() {
+			return new HistorySnapShot(toArray(), fHistoryRemainder.toString());
+		}
+
+		/**
+		 * Writes complete lines to the history buffer, and accumulates incomplete lines "remainder" until
+		 * they form a full line.
+		 * 
+		 * Adding complete lines to the buffer is needed to respect a specified maximum number of buffered
+		 * lines
+		 */
+		public synchronized void appendHistory(byte[] b, int read) {
+			// Read this new input
+			StringBuilder info = new StringBuilder(new String(b, StandardCharsets.UTF_8));
+			info.setLength(read);
+
+			// Separate by lines but keep the separator character
+			String regEx = "(?<=\\n)"; //$NON-NLS-1$
+			String[] chunks = info.toString().split(regEx);
+
+			for (int i = 0; i < chunks.length; i++) {
+				StringBuilder lineBuilder = new StringBuilder();
+				if (i == 0) {
+					// Add the previous incomplete line info ("remainder") first
+					lineBuilder.append(popRemainder());
+				}
+
+				lineBuilder.append(chunks[i]);
+				String line = lineBuilder.toString();
+
+				if (line.endsWith("\n")) { //$NON-NLS-1$
+					// We have build a complete line, So lets add it to the history
+					// Make sure we don't exceed the maximum buffer size
+					while (this.size() >= HIST_BUFFER_MAX_SIZE) {
+						this.remove();
+					}
+
+					this.offer(line);
+				} else {
+					// The only line with no separator shall be the last one
+					// otherwise it should have been split
+					assert i == (chunks.length - 1);
+					appendRemainder(line);
+				}
+			}
+		}
+
+		@Override
+		public synchronized String[] toArray()  {
+			return super.toArray(new String[size()]);
+		}
+	}
+
+	public void dispose() {
+		fOutputStreamJob.cancel();
+		fErrorStreamJob.cancel();
+	}
+
+	@Override
+	public void addPageTerminalControl(ITerminalControl terminalControl) {
+		// write the currently available buffered history to this new terminal
+		new WriteHistoryJob(terminalControl).schedule();
+	}
+
+	@Override
+	public void removePageTerminalControl(ITerminalControl terminalControl) {
+		if (terminalControl != null) {
+			fTerminalPageControls.remove(terminalControl);
+		}
+	}
+
+	@Override
+	public OutputStream getTerminalToRemoteStream() {
+		// When the user writes to the terminal, it should be sent
+		// directly to GDB
+		return fProcess.getOutputStream();
+	}
+
+	private class OutputReadJob extends Job {
+		{
+			setSystem(true);
+		}
+
+		private InputStream fInputStream;
+
+		private OutputReadJob(InputStream procStream, String nameSuffix) {
+			super("GDB CLI output Job" + nameSuffix); //$NON-NLS-1$
+			fInputStream = procStream;
+		}
+
+		@Override
+		protected IStatus run(IProgressMonitor monitor) {
+			try {
+				byte[] b = new byte[1024];
+				int read = 0;
+
+				do {
+					if (monitor.isCanceled()) {
+						break;
+					}
+
+					read = fInputStream.read(b);
+					if (read > 0) {
+						// Write fresh output to the existing consoles
+						synchronized (fTerminalPageControls) {
+							for (ITerminalControl control : fTerminalPageControls) {
+								control.getRemoteToTerminalOutputStream().write(b, 0, read);
+							}
+
+							// Add this input to the history buffer
+							fHistoryBuffer.appendHistory(b, read);
+						}
+					}
+				} while (read >= 0);
+			} catch (IOException e) {
+			}
+
+			return Status.OK_STATUS;
+		}
+	}
+
+	private class WriteHistoryJob extends Job {
+		{
+			setSystem(true);
+		}
+
+		private final ITerminalControl fTerminalControl;
+
+		public WriteHistoryJob(ITerminalControl terminalControl) {
+			super("GDB CLI write history job"); //$NON-NLS-1$
+			fTerminalControl = terminalControl;
+		}
+
+		@Override
+		protected IStatus run(IProgressMonitor monitor) {
+			OutputStream terminalOutputStream = fTerminalControl.getRemoteToTerminalOutputStream();
+			if (terminalOutputStream == null) {
+				return Status.OK_STATUS;
+			}
+
+			// Append the buffered lines to the terminal control instance
+			synchronized (fTerminalPageControls) {
+				// First get a snapshot of the current information in the history buffer
+				ConsoleHistoryLinesBuffer.HistorySnapShot history = fHistoryBuffer.getHistorySnapShot();
+				String[] buffLines = history.fHistoryLinesSnapShot;
+
+				// Writing the current buffer in chunks of data
+				// Calculate the initial limits
+				// The position pointed by 'end' is not written out on the iteration, but used as the limit
+				int start = 0;
+				int end = buffLines.length <= HIST_BUFFER_WRITE_SIZE ? buffLines.length : HIST_BUFFER_WRITE_SIZE;
+
+				// Write the history in chunks of lines
+				StringBuilder sb = new StringBuilder(HIST_BUFFER_WRITE_SIZE);
+
+				while (start < buffLines.length) {
+					// Prepare the data chunk to write
+					String[] chunk = Arrays.copyOfRange(buffLines, start, end);
+
+					for (String line : chunk) {
+						sb.append(line);
+					}
+
+					// Calculate limits for next iteration
+					start = end;
+					int linesLeft = buffLines.length - end;
+					end = start + (linesLeft <= HIST_BUFFER_WRITE_SIZE ? linesLeft : HIST_BUFFER_WRITE_SIZE);
+
+					// if this is the last write,
+					if (!(start < buffLines.length)) {
+						// Add the accumulated remainder value (i.e. not yet a complete line) as the last line
+						sb.append(history.fHistoryRemainderSnapShot);
+					}
+
+					// Write to Output Stream
+					if (sb.length() > 0) {
+						byte[] bytes = sb.toString().getBytes();
+						try {
+							terminalOutputStream.write(bytes, 0, bytes.length);
+						} catch (IOException e) {
+						}
+						sb.setLength(0);
+					}
+				}
+				// Add it to the list so it can now receive new input
+				fTerminalPageControls.add(fTerminalControl);
+			}
+
+			return Status.OK_STATUS;
+		}
+	}
+
+}
\ No newline at end of file