ctf: Add streamIntersection() method for CTF traces

Stream intersection consists of trimming the trace to the time range
intersecting all CTF streams. This allows dropping events from areas
where only partial data is available.

This would be a good contender for re-using the trim() method. However
since trim() is currently implemented by calling Babeltrace, and
Babeltrace already has a stream intersection function, we can simply
call Babeltrace's function.

Change-Id: I9d38fbddccb2bee88aa4bca3f068efed24c295d5
Signed-off-by: Alexandre Montplaisir <alexmonthy@efficios.com>

diff --git a/ctf/org.eclipse.tracecompass.tmf.ctf.core/src/org/eclipse/tracecompass/tmf/ctf/core/trace/CtfTmfTrace.java b/ctf/org.eclipse.tracecompass.tmf.ctf.core/src/org/eclipse/tracecompass/tmf/ctf/core/trace/CtfTmfTrace.java
index e51558c6d6dd60ad78d51dc1e72f3d9d9784e6de..7168acb181c97554c521a4f385a93f52be79edbb 100644 (file)
--- a/ctf/org.eclipse.tracecompass.tmf.ctf.core/src/org/eclipse/tracecompass/tmf/ctf/core/trace/CtfTmfTrace.java
+++ b/ctf/org.eclipse.tracecompass.tmf.ctf.core/src/org/eclipse/tracecompass/tmf/ctf/core/trace/CtfTmfTrace.java
@@ -755,22 +755,72 @@ public class CtfTmfTrace extends TmfTrace
     }
 
     /**
+     * Perform stream intersection on the current trace. This means trimming the
+     * trace to the largest time range for which all CTF streams have events
+     * present in them.
+     *
+     * Since the initial trace needs to be imported/initialized in Trace
+     * Compass, it works by creating a new trace which results from the stream
+     * intersection operation.
+     *
+     * A typical use case is for analyzing snapshot traces, where some
+     * low-activity streams may go back in time very far, and others with more
+     * events don't go very far in time. By doing a stream intersection we drop
+     * events from less interesting periods.
+     *
+     * @param destinationPath
+     *            The location where the new trace will be created.
+     * @param monitor
+     *            Progress monitor for cases where the operation is ran from
+     *            inside a Job. You can use a
+     *            {@link org.eclipse.core.runtime.NullProgressMonitor} if none
+     *            is available.
+     * @throws CoreException
+     *             Optional exception indicating an error during the execution
+     *             of the operation.
      * @since 2.2
      */
-    @Override
     @SuppressWarnings("nls")
-    public void trim(@NonNull TmfTimeRange range, @NonNull Path destinationPath, @NonNull IProgressMonitor monitor) throws CoreException {
-        List<@NonNull String> command;
-        @Nullable List<String> output;
+    public void streamIntersection(@NonNull Path destinationPath,  @NonNull IProgressMonitor monitor) throws CoreException {
+        /* Perform the stream intersection reading + outputting by Babeltrace */
+        verifyBabeltrace2Present();
 
-        /* Verify that Babeltrace 2.0 is installed and available */
-        command = Arrays.asList("babeltrace", "--version");
-        output = ProcessUtils.getOutputFromCommand(command);
-        if (output == null || output.isEmpty() || !output.get(0).contains("Babeltrace 2")) {
-            IStatus status = new Status(IStatus.ERROR, Activator.PLUGIN_ID, Messages.CtfTmfTrace_BabelTrace2NotFound);
-            throw new CoreException(status);
+        /*
+         * NOTE Querying the stream ranges could be done on the Trace Compass side.
+         * However since we need Babeltrace atm for the trace trimming, we might as well
+         * just call Babeltrace's stream intersection operation. If a Babeltrace-free
+         * trim() is implemented, this here could be modified to call trim() instead.
+         */
+        String originPath = getPath();
+        if (!originPath.endsWith(File.separator)) {
+            originPath = originPath + File.separator;
         }
 
+        List<@NonNull String> command = Arrays.asList("bash", "-c",
+                "babeltrace"
+                + " \"" + originPath + "\""
+                + " --stream-intersection"
+                + " --no-debug-info"
+                + " --component sink.ctf.fs"
+                + " --path \"" + destinationPath.toString() + '\"'
+                + " -p single-trace=true"
+                );
+
+        ProcessUtils.getOutputFromCommandCancellable(command,
+                monitor,
+                nullToEmptyString(Messages.CtfTmfTrace_InvokingBabeltrace),
+                /* We don't need to process the output. */
+                (r, m) -> Collections.emptyList());
+    }
+
+    /**
+     * @since 2.2
+     */
+    @Override
+    @SuppressWarnings("nls")
+    public void trim(@NonNull TmfTimeRange range, @NonNull Path destinationPath, @NonNull IProgressMonitor monitor) throws CoreException {
+        verifyBabeltrace2Present();
+
         /* Trim and save the new trace */
         String originPath = getPath();
         if (!originPath.endsWith(File.separator)) {
@@ -780,7 +830,7 @@ public class CtfTmfTrace extends TmfTrace
         String rangeStart = TS_FORMAT.format(range.getStartTime().toNanos());
         String rangeEnd = TS_FORMAT.format(range.getEndTime().toNanos());
 
-        command = Arrays.asList("bash", "-c",
+        List<@NonNull String> command = Arrays.asList("bash", "-c",
                 "babeltrace"
                 + " \"" + originPath + "\""
                 + " --begin " + rangeStart
@@ -804,4 +854,20 @@ public class CtfTmfTrace extends TmfTrace
                 (r, m) -> Collections.emptyList());
     }
 
+    /**
+     * Verify that Babeltrace 2.0 is installed and available.
+     *
+     * @throws CoreException
+     *             Reports this error if Babeltrace 2 is not found
+     */
+    @SuppressWarnings("nls")
+    private static void verifyBabeltrace2Present() throws CoreException {
+        List<@NonNull String> command = Arrays.asList("babeltrace", "--version");
+        @Nullable List<String> output = ProcessUtils.getOutputFromCommand(command);
+        if (output == null || output.isEmpty() || !output.get(0).contains("Babeltrace 2")) {
+            IStatus status = new Status(IStatus.ERROR, Activator.PLUGIN_ID, Messages.CtfTmfTrace_BabelTrace2NotFound);
+            throw new CoreException(status);
+        }
+    }
+
 }