Add an API to get the timestamp of a unit by its output path

Sources/IndexStoreDB/IndexStoreDB.swift

@@ -488,6 +488,19 @@ public final class IndexStoreDB {
     }
     return Date(timeIntervalSince1970: Double(timestamp) / 1_000_000_000)
   }
+
+  /// Returns a modification date of the latest unit that contains the given source file.
+  ///
+  /// If no unit containing the given source file exists, returns `nil`
+  public func dateOfUnitFor(outputPath: String) -> Date? {
+    let timestamp = outputPath.withCString { outputPathCString in
+      indexstoredb_timestamp_of_unit_for_output_path(impl, outputPathCString)
+    }
+    if timestamp == 0 {
+      return nil
+    }
+    return Date(timeIntervalSince1970: Double(timestamp) / 1_000_000_000)
+  }
 }
 
 public protocol IndexStoreLibraryProvider {

Sources/IndexStoreDB_CIndexStoreDB/CIndexStoreDB.cpp

@@ -698,4 +698,21 @@ indexstoredb_timestamp_of_latest_unit_for_file(
   return 0;
 }
 
+INDEXSTOREDB_PUBLIC uint64_t
+indexstoredb_timestamp_of_unit_for_output_path(
+  _Nonnull indexstoredb_index_t index,
+  const char *_Nonnull unitOutputPath
+) {
+  auto obj = (Object<std::shared_ptr<IndexSystem>> *)index;
+  llvm::Optional<llvm::sys::TimePoint<>> timePoint = obj->value->timestampOfUnitForOutputPath(unitOutputPath);
+  if (timePoint) {
+    // Up until C++20 the reference date of time_since_epoch is undefined but according to
+    // https://en.cppreference.com/w/cpp/chrono/system_clock most implementations use Unix Time.
+    // Since C++20, system_clock is defined to measure time since 1/1/1970.
+    // We rely on `time_since_epoch` always returning the nanoseconds since 1/1/1970.
+    return timePoint->time_since_epoch().count();
+  }
+  return 0;
+}
+
 ObjectBase::~ObjectBase() {}

Sources/IndexStoreDB_CIndexStoreDB/include/IndexStoreDB_CIndexStoreDB/CIndexStoreDB.h

@@ -601,6 +601,15 @@ indexstoredb_timestamp_of_latest_unit_for_file(
   const char *_Nonnull fileName
 );
 
+/// Returns a Unix timestamp (nanoseconds since 1/1/1970) of the unit that has the given output path.
+///
+/// If no unit with this output paths exits, returns 0.
+INDEXSTOREDB_PUBLIC uint64_t
+indexstoredb_timestamp_of_unit_for_output_path(
+  _Nonnull indexstoredb_index_t index,
+  const char *_Nonnull unitOutputPath
+);
+
 INDEXSTOREDB_END_DECLS
 
 #endif

Sources/IndexStoreDB_Index/IndexDatastore.cpp

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "IndexDatastore.h"
+#include "IndexStoreDB_LLVMSupport/llvm_ADT_None.h"
 #include "StoreSymbolRecord.h"
 #include <IndexStoreDB_Core/Symbol.h>
 #include <IndexStoreDB_Index/FilePathIndex.h>
@@ -172,6 +173,7 @@ class IndexDatastoreImpl {
 
   bool isUnitOutOfDate(StringRef unitOutputPath, ArrayRef<StringRef> dirtyFiles);
   bool isUnitOutOfDate(StringRef unitOutputPath, llvm::sys::TimePoint<> outOfDateModTime);
+  llvm::Optional<sys::TimePoint<>> timestampOfUnitForOutputPath(StringRef unitOutputPath);
   void checkUnitContainingFileIsOutOfDate(StringRef file);
 
   void addUnitOutFilePaths(ArrayRef<StringRef> filePaths, bool waitForProcessing);
@@ -1101,16 +1103,23 @@ bool IndexDatastoreImpl::isUnitOutOfDate(StringRef unitOutputPath, ArrayRef<Stri
 }
 
 bool IndexDatastoreImpl::isUnitOutOfDate(StringRef unitOutputPath, sys::TimePoint<> outOfDateModTime) {
+  auto unitModTime = timestampOfUnitForOutputPath(unitOutputPath);
+  if (!unitModTime) {
+    return true;
+  }
+  return outOfDateModTime > unitModTime;
+}
+
+llvm::Optional<sys::TimePoint<>> IndexDatastoreImpl::timestampOfUnitForOutputPath(StringRef unitOutputPath) {
   SmallString<128> nameBuf;
   IdxStore->getUnitNameFromOutputPath(unitOutputPath, nameBuf);
   StringRef unitName = nameBuf.str();
   std::string error;
   auto optUnitModTime = IdxStore->getUnitModificationTime(unitName, error);
   if (!optUnitModTime)
-    return true;
+    return llvm::None;
 
-  auto unitModTime = toTimePoint(optUnitModTime.getValue());
-  return outOfDateModTime > unitModTime;
+  return toTimePoint(optUnitModTime.getValue());
 }
 
 void IndexDatastoreImpl::checkUnitContainingFileIsOutOfDate(StringRef file) {
@@ -1169,6 +1178,10 @@ bool IndexDatastore::isUnitOutOfDate(StringRef unitOutputPath, sys::TimePoint<>
   return IMPL->isUnitOutOfDate(unitOutputPath, outOfDateModTime);
 }
 
+llvm::Optional<sys::TimePoint<>> IndexDatastore::timestampOfUnitForOutputPath(StringRef unitOutputPath) {
+  return IMPL->timestampOfUnitForOutputPath(unitOutputPath);
+}
+
 void IndexDatastore::checkUnitContainingFileIsOutOfDate(StringRef file) {
   return IMPL->checkUnitContainingFileIsOutOfDate(file);
 }

Sources/IndexStoreDB_Index/IndexDatastore.h

@@ -46,6 +46,7 @@ class IndexDatastore {
 
   bool isUnitOutOfDate(StringRef unitOutputPath, ArrayRef<StringRef> dirtyFiles);
   bool isUnitOutOfDate(StringRef unitOutputPath, llvm::sys::TimePoint<> outOfDateModTime);
+  llvm::Optional<llvm::sys::TimePoint<>> timestampOfUnitForOutputPath(StringRef unitOutputPath);
 
   /// Check whether any unit(s) containing \p file are out of date and if so,
   /// *synchronously* notify the delegate.

Sources/IndexStoreDB_Index/IndexSystem.cpp

@@ -141,6 +141,7 @@ class IndexSystemImpl {
 
   bool isUnitOutOfDate(StringRef unitOutputPath, ArrayRef<StringRef> dirtyFiles);
   bool isUnitOutOfDate(StringRef unitOutputPath, llvm::sys::TimePoint<> outOfDateModTime);
+  llvm::Optional<llvm::sys::TimePoint<>> timestampOfUnitForOutputPath(StringRef unitOutputPath);
   void checkUnitContainingFileIsOutOfDate(StringRef file);
 
   void registerMainFiles(ArrayRef<StringRef> filePaths, StringRef productName);
@@ -305,6 +306,10 @@ bool IndexSystemImpl::isUnitOutOfDate(StringRef unitOutputPath, llvm::sys::TimeP
   return IndexStore->isUnitOutOfDate(unitOutputPath, outOfDateModTime);
 }
 
+llvm::Optional<llvm::sys::TimePoint<>> IndexSystemImpl::timestampOfUnitForOutputPath(StringRef unitOutputPath) {
+  return IndexStore->timestampOfUnitForOutputPath(unitOutputPath);
+}
+
 void IndexSystemImpl::checkUnitContainingFileIsOutOfDate(StringRef file) {
   return IndexStore->checkUnitContainingFileIsOutOfDate(file);
 }
@@ -686,6 +691,10 @@ bool IndexSystem::isUnitOutOfDate(StringRef unitOutputPath, llvm::sys::TimePoint
   return IMPL->isUnitOutOfDate(unitOutputPath, outOfDateModTime);
 }
 
+llvm::Optional<llvm::sys::TimePoint<>> IndexSystem::timestampOfUnitForOutputPath(StringRef unitOutputPath) {
+  return IMPL->timestampOfUnitForOutputPath(unitOutputPath);
+}
+
 void IndexSystem::checkUnitContainingFileIsOutOfDate(StringRef file) {
   return IMPL->checkUnitContainingFileIsOutOfDate(file);
 }

Sources/IndexStoreDB_Index/include/IndexStoreDB_Index/IndexSystem.h

@@ -67,6 +67,7 @@ class INDEXSTOREDB_EXPORT IndexSystem {
 
   bool isUnitOutOfDate(StringRef unitOutputPath, ArrayRef<StringRef> dirtyFiles);
   bool isUnitOutOfDate(StringRef unitOutputPath, llvm::sys::TimePoint<> outOfDateModTime);
+  llvm::Optional<llvm::sys::TimePoint<>> timestampOfUnitForOutputPath(StringRef unitOutputPath);
 
   /// Check whether any unit(s) containing \p file are out of date and if so,
   /// *synchronously* notify the delegate.