Optimizations

CHANGELOG.md

@@ -7,6 +7,7 @@
 ##### Enhancements
 
 - Added support for Bazel 9.x.
+- Significant performance improvements. Scanning the Reddit iOS codebase reduced by 80.4% from 77.2s to 15.1s.
 
 ##### Bug Fixes
 

Package.swift

@@ -103,6 +103,7 @@ var targets: [PackageDescription.Target] = [
         name: "SourceGraph",
         dependencies: [
             .target(name: "Configuration"),
+            .target(name: "Extensions"),
             .product(name: "SwiftSyntax", package: "swift-syntax"),
             .product(name: "SystemPackage", package: "swift-system"),
             .target(name: "Shared"),

Sources/BUILD.bazel

@@ -52,9 +52,14 @@ swift_library(
         "SourceGraph/Elements/DeclarationAttribute.swift",
         "SourceGraph/Elements/ImportStatement.swift",
         "SourceGraph/Elements/Location.swift",
+        "SourceGraph/Elements/ModuleBitset.swift",
+        "SourceGraph/Elements/ModuleID.swift",
+        "SourceGraph/Elements/ModuleNameInterner.swift",
         "SourceGraph/Elements/ProjectFileKind.swift",
         "SourceGraph/Elements/Reference.swift",
         "SourceGraph/Elements/SourceFile.swift",
+        "SourceGraph/Elements/USRID.swift",
+        "SourceGraph/Elements/USRInterner.swift",
         "SourceGraph/Mutators/AccessibilityCascader.swift",
         "SourceGraph/Mutators/AncestralReferenceEliminator.swift",
         "SourceGraph/Mutators/AppIntentsRetainer.swift",
@@ -98,6 +103,7 @@ swift_library(
     module_name = "SourceGraph",
     deps = [
         "//Sources:Configuration",
+        "//Sources:Extensions",
         "//Sources:Shared",
         "@swift-syntax//:SwiftSyntax",
         "@swift-system//:SystemPackage",

Sources/Frontend/Commands/ScanCommand.swift

@@ -177,6 +177,7 @@ struct ScanCommand: ParsableCommand {
 
         configuration.guidedSetup = setup
         configuration.projectRoot = projectRoot
+
         configuration.apply(\.$project, project)
         configuration.apply(\.$schemes, schemes)
         configuration.apply(\.$indexExclude, indexExclude)

Sources/Frontend/Scan.swift

@@ -17,7 +17,7 @@ final class Scan {
         self.configuration = configuration
         self.logger = logger
         self.swiftVersion = swiftVersion
-        graph = SourceGraph(configuration: configuration, logger: logger)
+        graph = SourceGraph(configuration: configuration)
     }
 
     func perform(project: Project) throws -> [ScanResult] {
@@ -41,7 +41,11 @@ final class Scan {
         try build(driver)
         try index(driver)
         try analyze()
-        return buildResults()
+        let results = buildResults()
+        // Let the OS reclaim memory at process exit instead of paying
+        // the cost of tearing down the entire SourceGraph via ARC.
+        _ = Unmanaged.passRetained(graph)
+        return results
     }
 
     // MARK: - Private
@@ -68,7 +72,9 @@ final class Scan {
         }
 
         let indexLogger = logger.contextualized(with: "index")
+        let planInterval = logger.beginInterval("index:plan")
         let plan = try driver.plan(logger: indexLogger)
+        logger.endInterval(planInterval)
         let graphMutex = SourceGraphMutex(graph: graph)
         let pipeline = IndexPipeline(plan: plan, graph: graphMutex, logger: indexLogger, configuration: configuration, swiftVersion: swiftVersion)
         try pipeline.perform()

Sources/Indexer/IndexPipeline.swift

@@ -64,6 +64,8 @@ public struct IndexPipeline {
             ).perform()
         }
 
+        let interval = logger.beginInterval("index:complete")
         graph.withLock { $0.indexingComplete() }
+        logger.endInterval(interval)
     }
 }

Sources/Indexer/SourceFileCollector.swift

@@ -43,12 +43,12 @@ public struct SourceFileCollector {
                     let file = FilePath.makeAbsolute(filePath, relativeTo: currentFilePath)
 
                     if !isExcluded(file) {
-                        guard file.exists else {
-                            logger.debug("Source file does not exist: \(file.string)")
+                        if excludedTargets.contains(unit.moduleName) {
                             return nil
                         }
 
-                        if excludedTargets.contains(unit.moduleName) {
+                        guard file.exists else {
+                            logger.debug("Source file does not exist: \(file.string)")
                             return nil
                         }