Optimize iTermProcessCache with coalesced incremental refresh

iTerm2.xcodeproj/project.pbxproj

@@ -724,6 +724,7 @@
 		531E71F72229A69C00915960 /* iTermExpressionParser+Private.h in Headers */ = {isa = PBXBuildFile; fileRef = 531E71F62229A69C00915960 /* iTermExpressionParser+Private.h */; };
 		532755852387821C00C50732 /* iTermProcessMonitor.h in Headers */ = {isa = PBXBuildFile; fileRef = 532755832387821C00C50732 /* iTermProcessMonitor.h */; };
 		532755862387821C00C50732 /* iTermProcessMonitor.m in Sources */ = {isa = PBXBuildFile; fileRef = 532755842387821C00C50732 /* iTermProcessMonitor.m */; };
+		D7A9E6F12ABC123456789012 /* iTermProcessMonitor+Testing.m in Sources */ = {isa = PBXBuildFile; fileRef = D7A9E6F02ABC123456789011 /* iTermProcessMonitor+Testing.m */; };
 		532F942B215DFEF600D509E4 /* iTermCacheableImage.h in Headers */ = {isa = PBXBuildFile; fileRef = 532F9429215DFEF600D509E4 /* iTermCacheableImage.h */; };
 		532F942C215DFEF600D509E4 /* iTermCacheableImage.m in Sources */ = {isa = PBXBuildFile; fileRef = 532F942A215DFEF600D509E4 /* iTermCacheableImage.m */; };
 		533292A6237E75360027EB49 /* iTermPythonArgumentParserTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 533292A5237E75360027EB49 /* iTermPythonArgumentParserTests.m */; };
@@ -815,6 +816,8 @@
 		537BFDC520FFA5A40098C91F /* iTermStatusBarJobComponent.h in Headers */ = {isa = PBXBuildFile; fileRef = 537BFDC320FFA5A40098C91F /* iTermStatusBarJobComponent.h */; };
 		537BFDC920FFB2590098C91F /* iTermProcessCache.h in Headers */ = {isa = PBXBuildFile; fileRef = 537BFDC720FFB2590098C91F /* iTermProcessCache.h */; };
 		537BFDCA20FFB2590098C91F /* iTermProcessCache.m in Sources */ = {isa = PBXBuildFile; fileRef = 537BFDC820FFB2590098C91F /* iTermProcessCache.m */; };
+		BAB0C1C2780DA546AFE73B80 /* iTermProcessCache+Testing.m in Sources */ = {isa = PBXBuildFile; fileRef = 42BC3DE2E88700AF9526F074 /* iTermProcessCache+Testing.m */; };
+		2A1F4551EB4181AC933F6915 /* iTermProcessCacheTestHelper.m in Sources */ = {isa = PBXBuildFile; fileRef = 08829F633C36167ABC85693D /* iTermProcessCacheTestHelper.m */; };
 		537BFDD12101AD9F0098C91F /* iTermCPUUtilization.h in Headers */ = {isa = PBXBuildFile; fileRef = 537BFDCF2101AD9F0098C91F /* iTermCPUUtilization.h */; };
 		537BFDD22101AD9F0098C91F /* iTermCPUUtilization.m in Sources */ = {isa = PBXBuildFile; fileRef = 537BFDD02101AD9F0098C91F /* iTermCPUUtilization.m */; };
 		537BFDD52101B2500098C91F /* iTermStatusBarCPUUtilizationComponent.h in Headers */ = {isa = PBXBuildFile; fileRef = 537BFDD32101B2500098C91F /* iTermStatusBarCPUUtilizationComponent.h */; };
@@ -5996,6 +5999,8 @@
 		531E71F62229A69C00915960 /* iTermExpressionParser+Private.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "iTermExpressionParser+Private.h"; sourceTree = "<group>"; };
 		532755832387821C00C50732 /* iTermProcessMonitor.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = iTermProcessMonitor.h; sourceTree = "<group>"; };
 		532755842387821C00C50732 /* iTermProcessMonitor.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermProcessMonitor.m; sourceTree = "<group>"; };
+		D7A9E6EF2ABC123456789010 /* iTermProcessMonitor+Testing.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "iTermProcessMonitor+Testing.h"; sourceTree = "<group>"; };
+		D7A9E6F02ABC123456789011 /* iTermProcessMonitor+Testing.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = "iTermProcessMonitor+Testing.m"; sourceTree = "<group>"; };
 		532F9429215DFEF600D509E4 /* iTermCacheableImage.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = iTermCacheableImage.h; sourceTree = "<group>"; };
 		532F942A215DFEF600D509E4 /* iTermCacheableImage.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermCacheableImage.m; sourceTree = "<group>"; };
 		533292A5237E75360027EB49 /* iTermPythonArgumentParserTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermPythonArgumentParserTests.m; sourceTree = "<group>"; };
@@ -6076,6 +6081,10 @@
 		537BFDC420FFA5A40098C91F /* iTermStatusBarJobComponent.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermStatusBarJobComponent.m; sourceTree = "<group>"; };
 		537BFDC720FFB2590098C91F /* iTermProcessCache.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = iTermProcessCache.h; sourceTree = "<group>"; };
 		537BFDC820FFB2590098C91F /* iTermProcessCache.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermProcessCache.m; sourceTree = "<group>"; };
+		C47650BBAFA6A247F2489C37 /* iTermProcessCache+Testing.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "iTermProcessCache+Testing.h"; sourceTree = "<group>"; };
+		42BC3DE2E88700AF9526F074 /* iTermProcessCache+Testing.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = "iTermProcessCache+Testing.m"; sourceTree = "<group>"; };
+		0FB571F65DACC53FDDE3E286 /* iTermProcessCacheTestHelper.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = iTermProcessCacheTestHelper.h; sourceTree = "<group>"; };
+		08829F633C36167ABC85693D /* iTermProcessCacheTestHelper.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermProcessCacheTestHelper.m; sourceTree = "<group>"; };
 		537BFDCF2101AD9F0098C91F /* iTermCPUUtilization.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = iTermCPUUtilization.h; sourceTree = "<group>"; };
 		537BFDD02101AD9F0098C91F /* iTermCPUUtilization.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = iTermCPUUtilization.m; sourceTree = "<group>"; };
 		537BFDD32101B2500098C91F /* iTermStatusBarCPUUtilizationComponent.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = iTermStatusBarCPUUtilizationComponent.h; sourceTree = "<group>"; };
@@ -12643,6 +12652,8 @@
 				A6A802E8226ED20800BC70DC /* iTermPrintGuard.m */,
 				532755832387821C00C50732 /* iTermProcessMonitor.h */,
 				532755842387821C00C50732 /* iTermProcessMonitor.m */,
+				D7A9E6EF2ABC123456789010 /* iTermProcessMonitor+Testing.h */,
+				D7A9E6F02ABC123456789011 /* iTermProcessMonitor+Testing.m */,
 				1D468BBF1B056CD600226083 /* iTermProfileSearchToken.m */,
 				A63493F623F2685A0047C31B /* iTermPromise.h */,
 				A63493F723F2685A0047C31B /* iTermPromise.m */,
@@ -14203,6 +14214,10 @@
 			children = (
 				537BFDC720FFB2590098C91F /* iTermProcessCache.h */,
 				537BFDC820FFB2590098C91F /* iTermProcessCache.m */,
+				C47650BBAFA6A247F2489C37 /* iTermProcessCache+Testing.h */,
+				42BC3DE2E88700AF9526F074 /* iTermProcessCache+Testing.m */,
+				0FB571F65DACC53FDDE3E286 /* iTermProcessCacheTestHelper.h */,
+				08829F633C36167ABC85693D /* iTermProcessCacheTestHelper.m */,
 				53AFFC8A1DD2A03800E6CEC6 /* iTermLSOF.h */,
 				53AFFC8B1DD2A03800E6CEC6 /* iTermLSOF.m */,
 				A6EEAEDD283712070039E850 /* ProcessDataSource.swift */,
@@ -18844,6 +18859,7 @@
 				A667C235276AB01F006B4DEF /* iTermMetalUnavailableReason.m in Sources */,
 				A6DB7BAC2CE52BB000EB7973 /* iTermPasteSpecialWindowController.m in Sources */,
 				532755862387821C00C50732 /* iTermProcessMonitor.m in Sources */,
+				D7A9E6F12ABC123456789012 /* iTermProcessMonitor+Testing.m in Sources */,
 				A6758565245AA23400827C25 /* iTermSwipeState.m in Sources */,
 				A667C266277A3B29006B4DEF /* PTYTriggerEvaluator.m in Sources */,
 				A6024B82254CE2000036D6CF /* iTermAddTriggerViewController.m in Sources */,
@@ -19638,6 +19654,8 @@
 				A6D3205529C29EE30088BBE1 /* NerdFontInstaller.swift in Sources */,
 				5308BF8A22828268004BECAC /* iTermStatusBarBatteryComponent.m in Sources */,
 				537BFDCA20FFB2590098C91F /* iTermProcessCache.m in Sources */,
+				BAB0C1C2780DA546AFE73B80 /* iTermProcessCache+Testing.m in Sources */,
+				2A1F4551EB4181AC933F6915 /* iTermProcessCacheTestHelper.m in Sources */,
 				A6F9EF3820850C41005530F7 /* iTermCompetentTableRowView.m in Sources */,
 				A6D10E3427F7C2BC0026DB56 /* NSRange+MultiCursor.swift in Sources */,
 				A65B1BD32D1E31CB00F5A740 /* iTermMetalView.swift in Sources */,

sources/DebugLogging.h

@@ -32,6 +32,14 @@ extern BOOL gDebugLogging;
 #define ITDebugAssert(condition) ((void)(condition))
 #endif
 
+// Assert that we're currently executing on the specified dispatch queue.
+// Uses dispatch_assert_queue() which provides clear error messages.
+#if ITERM_DEBUG
+#define ITAssertOnQueue(queue) dispatch_assert_queue(queue)
+#else
+#define ITAssertOnQueue(queue) ((void)(queue))
+#endif
+
 #if !ITERM_DEBUG && USE_STOPWATCH
 #define STOPWATCH_START(name) \
   NSTimeInterval start_##name = [NSDate timeIntervalSinceReferenceDate]; \

sources/PseudoTerminal.m

@@ -49,6 +49,7 @@
 #import "iTermOrderEnforcer.h"
 #import "iTermPasswordManagerWindowController.h"
 #import "iTermPreferences.h"
+#import "iTermProcessCache.h"
 #import "iTermProfilePreferences.h"
 #import "iTermProfilesWindowController.h"
 #import "iTermPromptOnCloseReason.h"
@@ -4407,6 +4408,16 @@ - (void)windowDidBecomeKey:(NSNotification *)aNotification {
         [aSession.view setNeedsDisplay:YES];
         [aSession useTransparencyDidChange];
     }
+
+    // Update process cache with foreground root PIDs for the current tab
+    NSMutableSet<NSNumber *> *foregroundPIDs = [NSMutableSet set];
+    for (PTYSession *session in [self.currentTab sessions]) {
+        pid_t pid = session.shell.pid;
+        if (pid > 0) {
+            [foregroundPIDs addObject:@(pid)];
+        }
+    }
+    [[iTermProcessCache sharedInstance] setForegroundRootPIDs:foregroundPIDs];
     // Some users report that the first responder isn't always set properly. Let's try to fix that.
     // This attempt (4/20/13) is to fix bug 2431.
     if (!self.window.firstResponder.it_preferredFirstResponder) {
@@ -6704,6 +6715,17 @@ - (void)tabView:(NSTabView *)tabView didSelectTabViewItem:(NSTabViewItem *)tabVi
     [_contentView setCurrentSessionAlpha:self.currentSession.textview.transparencyAlpha];
     [tab didSelectTab];
     [[NSNotificationCenter defaultCenter] postNotificationName:iTermSelectedTabDidChange object:tab];
+
+    // Update process cache with foreground root PIDs for this window
+    NSMutableSet<NSNumber *> *foregroundPIDs = [NSMutableSet set];
+    for (PTYSession *session in [tab sessions]) {
+        pid_t pid = session.shell.pid;
+        if (pid > 0) {
+            [foregroundPIDs addObject:@(pid)];
+        }
+    }
+    [[iTermProcessCache sharedInstance] setForegroundRootPIDs:foregroundPIDs];
+
     DLog(@"Finished");
 }
 

sources/iTerm2SharedARC-Bridging-Header.h

@@ -66,6 +66,8 @@
 #import "iTermPreciseTimer.h"
 #import "iTermPreferences.h"
 #import "iTermProcess.h"
+#import "iTermProcessCacheTestHelper.h"
+#import "iTermProcessMonitor.h"
 #import "iTermProfilePreferencesBaseViewController.h"
 #import "iTermPromise.h"
 #import "iTermRemotePreferences.h"

sources/iTermLSOF.h

@@ -19,6 +19,7 @@ int iTermProcPidInfoWrapper(int pid, int flavor, uint64_t arg,  void *buffer, in
 + (NSString *)commandForProcess:(pid_t)pid execName:(NSString **)execName;
 + (NSArray<NSNumber *> *)allPids;
 + (pid_t)ppidForPid:(pid_t)childPid;
++ (NSArray<NSNumber *> *)childPidsForPid:(pid_t)parentPid;
 + (NSString *)nameOfProcessWithPid:(pid_t)thePid isForeground:(BOOL *)isForeground;
 + (NSString *)workingDirectoryOfProcess:(pid_t)pid;
 + (void)asyncWorkingDirectoryOfProcess:(pid_t)pid

sources/iTermLSOF.m

@@ -246,6 +246,50 @@ + (pid_t)ppidForPid:(pid_t)childPid {
     }
 }
 
+// Returns direct child PIDs for a given parent PID.
+// Note: proc_listchildpids returns PID count (not bytes like proc_listpids).
++ (NSArray<NSNumber *> *)childPidsForPid:(pid_t)parentPid {
+    int count = proc_listchildpids(parentPid, NULL, 0);
+    if (count <= 0) {
+        return @[];
+    }
+
+    pid_t *pids = NULL;
+    int returnedCount = 0;
+
+    // Retry loop: child list can change between size query and fetch
+    for (int attempt = 0; attempt < 3; attempt++) {
+        int capacity = count + 16;  // Headroom for new children
+        size_t bufferSize = capacity * sizeof(pid_t);
+        pids = (pid_t *)iTermMalloc(bufferSize);
+
+        returnedCount = proc_listchildpids(parentPid, pids, (int)bufferSize);
+        if (returnedCount < 0) {
+            free(pids);
+            return @[];
+        }
+        if (returnedCount <= capacity) {
+            break;
+        }
+        // Buffer too small, retry with larger capacity
+        free(pids);
+        pids = NULL;
+        count = returnedCount;
+    }
+
+    // If all retries exhausted (child count kept growing faster than we could allocate), bail out
+    if (pids == NULL) {
+        return @[];
+    }
+
+    NSMutableArray<NSNumber *> *result = [NSMutableArray arrayWithCapacity:returnedCount];
+    for (int i = 0; i < returnedCount; i++) {
+        [result addObject:@(pids[i])];
+    }
+    free(pids);
+    return result;
+}
+
 // Use sysctl magic to get the name of a process and whether it is controlling
 // the tty. This code was adapted from ps, here:
 // http://opensource.apple.com/source/adv_cmds/adv_cmds-138.1/ps/

sources/iTermProcessCache+Testing.h

@@ -0,0 +1,40 @@
+//
+//  iTermProcessCache+Testing.h
+//  iTerm2SharedARC
+//
+//  Testing-only interface for iTermProcessCache.
+//
+
+#import "iTermProcessCache.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface iTermProcessCache (Testing)
+
+/// Create a non-singleton instance for testing.
+- (instancetype)initForTesting;
+
+/// Number of roots in the dirty low-priority (background) set.
+@property (nonatomic, readonly) NSUInteger dirtyLowRootsCount;
+
+/// Number of roots in the dirty high-priority (foreground) set.
+@property (nonatomic, readonly) NSUInteger dirtyHighRootsCount;
+
+/// Whether a specific root PID is currently marked as high priority (foreground).
+- (BOOL)isRootHighPriority:(pid_t)rootPID;
+
+/// Whether a specific root PID exists in the tracking system.
+- (BOOL)isTrackingRoot:(pid_t)rootPID;
+
+/// Force a background refresh tick (normally called by timer).
+- (void)forceBackgroundRefreshTick;
+
+/// Register a root PID for tracking (testing only).
+- (void)registerTestRoot:(pid_t)rootPID;
+
+/// Unregister a root PID (testing only).
+- (void)unregisterTestRoot:(pid_t)rootPID;
+
+@end
+
+NS_ASSUME_NONNULL_END

sources/iTermProcessCache+Testing.m

@@ -0,0 +1,97 @@
+//
+//  iTermProcessCache+Testing.m
+//  iTerm2SharedARC
+//
+//  Testing-only implementation for iTermProcessCache.
+//
+
+#import "iTermProcessCache+Testing.h"
+#import "iTermProcessMonitor.h"
+
+// Forward declare private ivars we need to access
+@interface iTermProcessCache () {
+    @public
+    dispatch_queue_t _lockQueue;
+    dispatch_queue_t _workQueue;
+    NSMutableDictionary *_rootsLQ;
+    NSMutableIndexSet *_dirtyHighRootsLQ;
+    NSMutableIndexSet *_dirtyLowRootsLQ;
+}
+- (void)backgroundRefreshTick;
+@end
+
+// Forward declare iTermTrackedRootInfo for access
+@interface iTermTrackedRootInfo : NSObject
+@property (nonatomic) BOOL isHighPriority;
+@property (nonatomic, strong, nullable) iTermProcessMonitor *monitor;
+@property (nonatomic, strong) NSMutableIndexSet *cachedDescendants;
+@property (nonatomic) NSUInteger lastRefreshEpoch;
+@property (nonatomic) BOOL isDirty;
+@end
+
+@implementation iTermProcessCache (Testing)
+
+- (instancetype)initForTesting {
+    return [self init];
+}
+
+- (NSUInteger)dirtyLowRootsCount {
+    __block NSUInteger count = 0;
+    dispatch_sync(_lockQueue, ^{
+        count = self->_dirtyLowRootsLQ.count;
+    });
+    return count;
+}
+
+- (NSUInteger)dirtyHighRootsCount {
+    __block NSUInteger count = 0;
+    dispatch_sync(_lockQueue, ^{
+        count = self->_dirtyHighRootsLQ.count;
+    });
+    return count;
+}
+
+- (BOOL)isRootHighPriority:(pid_t)rootPID {
+    __block BOOL result = NO;
+    dispatch_sync(_lockQueue, ^{
+        iTermTrackedRootInfo *info = self->_rootsLQ[@(rootPID)];
+        result = info.isHighPriority;
+    });
+    return result;
+}
+
+- (BOOL)isTrackingRoot:(pid_t)rootPID {
+    __block BOOL result = NO;
+    dispatch_sync(_lockQueue, ^{
+        result = self->_rootsLQ[@(rootPID)] != nil;
+    });
+    return result;
+}
+
+- (void)forceBackgroundRefreshTick {
+    [self backgroundRefreshTick];
+}
+
+- (void)registerTestRoot:(pid_t)rootPID {
+    dispatch_sync(_lockQueue, ^{
+        if (self->_rootsLQ[@(rootPID)] == nil) {
+            iTermTrackedRootInfo *info = [[iTermTrackedRootInfo alloc] init];
+            info.isHighPriority = YES;  // Default to foreground
+            self->_rootsLQ[@(rootPID)] = info;
+        }
+    });
+}
+
+- (void)unregisterTestRoot:(pid_t)rootPID {
+    dispatch_sync(_lockQueue, ^{
+        iTermTrackedRootInfo *info = self->_rootsLQ[@(rootPID)];
+        if (info) {
+            [info.monitor invalidate];
+            [self->_rootsLQ removeObjectForKey:@(rootPID)];
+            [self->_dirtyHighRootsLQ removeIndex:rootPID];
+            [self->_dirtyLowRootsLQ removeIndex:rootPID];
+        }
+    });
+}
+
+@end

sources/iTermProcessCache.h

@@ -19,6 +19,11 @@ NS_ASSUME_NONNULL_BEGIN
 + (instancetype)sharedInstance;
 + (iTermProcessCollection *)newProcessCollection;
 
+// Update which root PIDs are foreground (high priority).
+// Foreground roots get fast incremental updates via process monitors.
+// Background roots have their monitors suspended and rely on the 0.5s cadence.
+- (void)setForegroundRootPIDs:(NSSet<NSNumber *> *)foregroundPIDs;
+
 @end
 
 NS_ASSUME_NONNULL_END