From 56213ff41aa7a48b2e529d901a025ef47a7b3f79 Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Mon, 21 Jan 2008 11:56:24 +0000
Subject: [PATCH] Some "traced" command optimizations: * Made the iterator
 static, so that it's possible to move from the   iteration position of the
 previous invocation to the current start,   instead of always having to start
 from the beginning or the end. * Filtered backward iteration:   - Restrict
 the range to dump to the entries between the first and the     last filter
 match.   - Use new FILTER_MATCH entry flag to avoid applying the filter a    
 second time in the print loop.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@23681 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/system/kernel/debug/tracing.cpp | 57 ++++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 10 deletions(-)

diff --git a/src/system/kernel/debug/tracing.cpp b/src/system/kernel/debug/tracing.cpp
index d58897b93e..8b1a1f4e28 100644
--- a/src/system/kernel/debug/tracing.cpp
+++ b/src/system/kernel/debug/tracing.cpp
@@ -28,7 +28,8 @@
 enum {
 	WRAP_ENTRY			= 0x01,
 	ENTRY_INITIALIZED	= 0x02,
-	BUFFER_ENTRY		= 0x04
+	BUFFER_ENTRY		= 0x04,
+	FILTER_MATCH		= 0x08
 };
 
 static const size_t kBufferSize = MAX_TRACE_SIZE / 4;
@@ -510,13 +511,19 @@ TraceFilterParser TraceFilterParser::sParser;
 
 class TraceEntryIterator {
 public:
-	TraceEntryIterator(bool startFront)
+	TraceEntryIterator()
 		:
-		fEntry(NULL),
-		fIndex(startFront ? 0 : sEntries + 1)
+ 		fEntry(NULL),
+		fIndex(0)
 	{
 	}
 
+	void Reset()
+	{
+		fEntry = NULL;
+		fIndex = 0;
+	}
+
 	int32 Index() const
 	{
 		return fIndex;
@@ -629,6 +636,9 @@ dump_tracing(int argc, char** argv)
 	static int32 _previousFirstChecked = 1;
 	static int32 _previousLastChecked = -1;
 	static uint32 _previousWritten = 0;
+	static uint32 _previousEntries = 0;
+	static TraceEntryIterator iterator;
+
 
 	// Note: start and index are Pascal-like indices (i.e. in [1, sEntries]).
 	int32 start = 0;	// special index: print the last count entries
@@ -653,7 +663,8 @@ dump_tracing(int argc, char** argv)
 			print_debugger_command_usage(argv[0]);
 			return 0;
 		}
-		if (sWritten == 0 || sWritten != _previousWritten) {
+		if (sWritten == 0 || sWritten != _previousWritten
+			|| sEntries != _previousEntries) {
 			kprintf("Can't continue iteration. \"%s\" has not been invoked "
 				"before, or there were new entries written since the last "
 				"invocation.\n", argv[0]);
@@ -737,13 +748,22 @@ dump_tracing(int argc, char** argv)
 		lastToCheck = min_c((int32)sEntries, start + maxToCheck - 1);
 	}
 
-	TraceEntryIterator iterator(true);
+	// reset the iterator, if something changed in the meantime
+	if (sWritten == 0 || sWritten != _previousWritten
+		|| sEntries != _previousEntries) {
+		iterator.Reset();
+	}
 
 	char buffer[256];
 	LazyTraceOutput out(buffer, sizeof(buffer));
 
+	bool markedMatching = false;
+	int32 firstToDump = firstToCheck;
+	int32 lastToDump = lastToCheck;
+
 	if (direction < 0 && hasFilter && lastToCheck - firstToCheck >= count) {
 		// iteration direction is backwards
+		markedMatching = true;
 
 		// From the last entry to check iterate backwards to check filter
 		// matches.
@@ -753,15 +773,23 @@ dump_tracing(int argc, char** argv)
 		iterator.MoveTo(lastToCheck + 1);
 
 		// iterate backwards
+		firstToDump = -1;
+		lastToDump = -1;
 		while (iterator.Index() > firstToCheck) {
 			TraceEntry* entry = iterator.Previous();
 			if ((entry->flags & ENTRY_INITIALIZED) != 0) {
 				out.Clear();
 				if (TraceFilterParser::Default()->Filter(entry, out)) {
+					entry->flags |= FILTER_MATCH;
+					if (lastToDump == -1)
+						lastToDump = iterator.Index();
+					firstToDump = iterator.Index();
+
 					matching++;
 					if (matching >= count)
 						break;
-				}
+				} else
+					entry->flags &= ~FILTER_MATCH;
 			}
 		}
 
@@ -772,13 +800,18 @@ dump_tracing(int argc, char** argv)
 		iterator.Previous();
 	}
 
+	// set the iterator to the entry before the first one to dump
+	iterator.MoveTo(firstToDump - 1);
+
+	// dump the entries matching the filter in the range
+	// [firstToDump, lastToDump]
 	int32 dumped = 0;
 
 	while (TraceEntry* entry = iterator.Next()) {
 		int32 index = iterator.Index();
-		if (index < firstToCheck)
+		if (index < firstToDump)
 			continue;
-		if (index > lastToCheck || dumped >= count) {
+		if (index > lastToDump || dumped >= count) {
 			if (direction > 0)
 				lastToCheck = index - 1;
 			break;
@@ -786,8 +819,11 @@ dump_tracing(int argc, char** argv)
 
 		if ((entry->flags & ENTRY_INITIALIZED) != 0) {
 			out.Clear();
-			if (hasFilter && !TraceFilterParser::Default()->Filter(entry, out))
+			if (hasFilter &&  (markedMatching
+					? (entry->flags & FILTER_MATCH) == 0
+					: !TraceFilterParser::Default()->Filter(entry, out))) {
 				continue;
+			}
 
 			kprintf("%5ld. %s\n", index, out.DumpEntry(entry));
 		} else if (!hasFilter)
@@ -807,6 +843,7 @@ dump_tracing(int argc, char** argv)
 	_previousFirstChecked = firstToCheck;
 	_previousLastChecked = lastToCheck;
 	_previousWritten = sWritten;
+	_previousEntries = sEntries;
 
 	return cont != 0 ? B_KDEBUG_CONT : 0;
 }