Make UniqueNumberGenerator::AddKnownId() return a value

Make AddKnownId() return a value to indicate whether the ID was
known before, or has only been made known now.
This allows users of the class to RTC_DCHECK that no collisions
existed in their seed set, for instance.

This change is done for the following classes:
1. UniqueNumberGenerator
2. UniqueRandomIdGenerator
3. UniqueStringGenerator

Bug: None
Change-Id: I627d2821cb76aa333075e36575088d76dbeb3665
Reviewed-on: https://webrtc-review.googlesource.com/c/121780
Commit-Queue: Elad Alon <eladalon@webrtc.org>
Reviewed-by: Amit Hilbuch <amithi@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26621}

rtc_base/unique_id_generator.cc

@@ -26,8 +26,8 @@ UniqueRandomIdGenerator::UniqueRandomIdGenerator(ArrayView<uint32_t> known_ids)
 UniqueRandomIdGenerator::~UniqueRandomIdGenerator() = default;
 
 uint32_t UniqueRandomIdGenerator::GenerateId() {
+  RTC_CHECK_LT(known_ids_.size(), std::numeric_limits<uint32_t>::max() - 1);
   while (true) {
-    RTC_CHECK_LT(known_ids_.size(), std::numeric_limits<uint32_t>::max());
     auto pair = known_ids_.insert(CreateRandomNonZeroId());
     if (pair.second) {
       return *pair.first;
@@ -35,8 +35,8 @@ uint32_t UniqueRandomIdGenerator::GenerateId() {
   }
 }
 
-void UniqueRandomIdGenerator::AddKnownId(uint32_t value) {
+bool UniqueRandomIdGenerator::AddKnownId(uint32_t value) {
-  known_ids_.insert(value);
+  return known_ids_.insert(value).second;
 }
 
 UniqueStringGenerator::UniqueStringGenerator() : unique_number_generator_() {}
@@ -52,13 +52,14 @@ std::string UniqueStringGenerator::GenerateString() {
   return ToString(unique_number_generator_.GenerateNumber());
 }
 
-void UniqueStringGenerator::AddKnownId(const std::string& value) {
+bool UniqueStringGenerator::AddKnownId(const std::string& value) {
   absl::optional<uint32_t> int_value = StringToNumber<uint32_t>(value);
   // The underlying generator works for uint32_t values, so if the provided
   // value is not a uint32_t it will never be generated anyway.
   if (int_value.has_value()) {
-    unique_number_generator_.AddKnownId(int_value.value());
+    return unique_number_generator_.AddKnownId(int_value.value());
   }
+  return false;
 }
 
 }  // namespace rtc

rtc_base/unique_id_generator.h

@@ -43,7 +43,8 @@ class UniqueNumberGenerator {
   TIntegral operator()() { return GenerateNumber(); }
 
   // Adds an id that this generator should no longer generate.
-  void AddKnownId(TIntegral value);
+  // Return value indicates whether the ID was hitherto unknown.
+  bool AddKnownId(TIntegral value);
 
  private:
   static_assert(std::is_integral<TIntegral>::value, "Must be integral type.");
@@ -71,7 +72,8 @@ class UniqueRandomIdGenerator {
   uint32_t operator()() { return GenerateId(); }
 
   // Adds an id that this generator should no longer generate.
-  void AddKnownId(uint32_t value);
+  // Return value indicates whether the ID was hitherto unknown.
+  bool AddKnownId(uint32_t value);
 
  private:
   std::set<uint32_t> known_ids_;
@@ -93,7 +95,8 @@ class UniqueStringGenerator {
   std::string operator()() { return GenerateString(); }
 
   // Adds an id that this generator should no longer generate.
-  void AddKnownId(const std::string& value);
+  // Return value indicates whether the ID was hitherto unknown.
+  bool AddKnownId(const std::string& value);
 
  private:
   // This implementation will be simple and will generate "0", "1", ...
@@ -123,8 +126,8 @@ TIntegral UniqueNumberGenerator<TIntegral>::GenerateNumber() {
 }
 
 template <typename TIntegral>
-void UniqueNumberGenerator<TIntegral>::AddKnownId(TIntegral value) {
+bool UniqueNumberGenerator<TIntegral>::AddKnownId(TIntegral value) {
-  known_ids_.insert(value);
+  return known_ids_.insert(value).second;
 }
 }  // namespace rtc
 

rtc_base/unique_id_generator_unittest.cc

@@ -29,6 +29,7 @@ class UniqueIdGeneratorTest : public Test {};
 using test_types = ::testing::Types<UniqueNumberGenerator<uint8_t>,
                                     UniqueNumberGenerator<uint16_t>,
                                     UniqueNumberGenerator<uint32_t>,
+                                    UniqueNumberGenerator<int>,
                                     UniqueRandomIdGenerator,
                                     UniqueStringGenerator>;
 
@@ -107,4 +108,43 @@ TYPED_TEST(UniqueIdGeneratorTest, AddedElementsAreNotGenerated) {
   EXPECT_THAT(intersection, IsEmpty());
 }
 
+TYPED_TEST(UniqueIdGeneratorTest, AddKnownIdOnNewIdReturnsTrue) {
+  typedef TypeParam Generator;
+
+  rtc::InitRandom(0);
+  Generator generator1;
+  const typename Generator::value_type id = generator1();
+
+  rtc::InitRandom(0);
+  Generator generator2;
+  EXPECT_TRUE(generator2.AddKnownId(id));
+}
+
+TYPED_TEST(UniqueIdGeneratorTest, AddKnownIdCalledAgainForSameIdReturnsFalse) {
+  typedef TypeParam Generator;
+
+  rtc::InitRandom(0);
+  Generator generator1;
+  const typename Generator::value_type id = generator1();
+
+  rtc::InitRandom(0);
+  Generator generator2;
+  ASSERT_TRUE(generator2.AddKnownId(id));
+  EXPECT_FALSE(generator2.AddKnownId(id));
+}
+
+TYPED_TEST(UniqueIdGeneratorTest,
+           AddKnownIdOnIdProvidedAsKnownToCtorReturnsFalse) {
+  typedef TypeParam Generator;
+
+  rtc::InitRandom(0);
+  Generator generator1;
+  const typename Generator::value_type id = generator1();
+  std::vector<typename Generator::value_type> known_values = {id};
+
+  rtc::InitRandom(0);
+  Generator generator2(known_values);
+  EXPECT_FALSE(generator2.AddKnownId(id));
+}
+
 }  // namespace rtc