Refactoring of job dispatch in HostResolverImpl in preparation for DnsClient.

net/base/prioritized_dispatcher_unittest.cc

Index: net/base/prioritized_dispatcher_unittest.cc
diff --git a/net/base/prioritized_dispatcher_unittest.cc b/net/base/prioritized_dispatcher_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..386e829843104e57a5de01d5ce705056e3ac90b6
--- /dev/null
+++ b/net/base/prioritized_dispatcher_unittest.cc
@@ -0,0 +1,279 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <ctype.h>
+#include <string>
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "net/base/prioritized_dispatcher.h"
+#include "net/base/request_priority.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+namespace {
+
+// We rely on the priority enum values being sequential having starting at 0,
+// and increasing for lower priorities.
+COMPILE_ASSERT(HIGHEST == 0u &&
+               LOWEST > HIGHEST &&
+               IDLE > LOWEST &&
+               NUM_PRIORITIES > IDLE,
+               priority_indexes_incompatible);
+
+class PrioritizedDispatcherTest : public testing::Test {
+ public:
+  // A job that appends |data| to |log_| when started and '.' when finished.
+  // This is intended to confirm the execution order of a sequence of jobs added
+  // to the dispatcher.
+  class TestJob : public PrioritizedDispatcher::Job {
+   public:
+    TestJob(PrioritizedDispatcherTest* test, char data, size_t priority)
+        : test_(test), data_(data), priority_(priority), running_(false) {}
+
+    // MSVS does not accept EXPECT_EQ(this, ...) so wrap it up.
+    PrioritizedDispatcher::Job* this_job() {
+      return this;
+    }
+
+    void Add() {
+      EXPECT_TRUE(handle_.is_null());
+      EXPECT_FALSE(running_);
+      size_t num_queued = dispatch().num_queued_jobs();
+      size_t num_running = dispatch().num_running_jobs();
+
+      handle_ = dispatch().Add(this, priority_);
+
+      if (handle_.is_null()) {
+        EXPECT_EQ(num_queued, dispatch().num_queued_jobs());
+        EXPECT_TRUE(running_);
+        EXPECT_EQ(num_running + 1, dispatch().num_running_jobs());
+      } else {
+        EXPECT_FALSE(running_);
+        EXPECT_EQ(priority_, handle_.priority());
+        EXPECT_EQ(this_job(), handle_.value());
+        EXPECT_EQ(num_running, dispatch().num_running_jobs());
+      }
+    }
+
+    void Update(size_t priority) {
+      EXPECT_FALSE(running_);
+      ASSERT_FALSE(handle_.is_null());
+      size_t num_queued = dispatch().num_queued_jobs();
+      size_t num_running = dispatch().num_running_jobs();
+
+      handle_ = dispatch().Update(handle_, priority);
+
+      if (handle_.is_null()) {
+        EXPECT_TRUE(running_);
+        EXPECT_EQ(num_queued - 1, dispatch().num_queued_jobs());
+        EXPECT_EQ(num_running + 1, dispatch().num_running_jobs());
+      } else {
+        EXPECT_FALSE(running_);
+        EXPECT_EQ(priority, handle_.priority());
+        EXPECT_EQ(this_job(), handle_.value());
+        EXPECT_EQ(num_queued, dispatch().num_queued_jobs());
+        EXPECT_EQ(num_running, dispatch().num_running_jobs());
+      }
+    }
+
+    void Cancel() {
+      EXPECT_FALSE(running_);
+      ASSERT_FALSE(handle_.is_null());
+      size_t num_queued = dispatch().num_queued_jobs();
+
+      dispatch().Cancel(handle_);
+
+      EXPECT_EQ(num_queued - 1, dispatch().num_queued_jobs());
+      handle_ = PrioritizedDispatcher::Handle();
+    }
+
+    void Finish() {
+      EXPECT_TRUE(running_);
+      running_ = false;
+      test_->log_.append(1u, '.');
+
+      dispatch().OnJobFinished();
+    }
+
+    // PriorityDispatch::Job interface
+    virtual void Start() OVERRIDE {
+      EXPECT_FALSE(running_);
+      handle_ = PrioritizedDispatcher::Handle();
+      running_ = true;
+      test_->log_.append(1u, data_);
+    }
+
+   private:
+    PrioritizedDispatcher& dispatch() { return *(test_->dispatch_); }
+
+    PrioritizedDispatcherTest* test_;
+
+    char data_;
+    size_t priority_;
+
+    PrioritizedDispatcher::Handle handle_;
+    bool running_;
+  };
+
+ protected:
+  void Prepare(const PrioritizedDispatcher::Limits& limits) {
+    dispatch_.reset(new PrioritizedDispatcher(NUM_PRIORITIES, limits));
+  }
+
+  TestJob* AddJob(char data, size_t priority) {
+    TestJob* job = new TestJob(this, data, priority);
+    jobs_.push_back(job);
+    job->Add();
+    return job;
+  }
+
+  void Expect(std::string log) {
+    EXPECT_EQ(0u, dispatch_->num_queued_jobs());
+    EXPECT_EQ(0u, dispatch_->num_running_jobs());
+    EXPECT_EQ(log, log_);
+    log_.clear();
+  }
+
+  std::string log_;
+  scoped_ptr<PrioritizedDispatcher> dispatch_;
+  ScopedVector<TestJob> jobs_;
+};
+
+TEST_F(PrioritizedDispatcherTest, AddAFIFO) {
+  // Allow only one running job.
+  PrioritizedDispatcher::Limits limits = { 1 };
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', IDLE);
+  TestJob* job_b = AddJob('b', IDLE);
+  TestJob* job_c = AddJob('c', IDLE);
+  TestJob* job_d = AddJob('d', IDLE);
+
+  job_a->Finish();
+  job_b->Finish();
+  job_c->Finish();
+  job_d->Finish();
+
+  Expect("a.b.c.d.");
+}
+
+TEST_F(PrioritizedDispatcherTest, AddPriority) {
+  PrioritizedDispatcher::Limits limits = { 1 };
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', IDLE);
+  TestJob* job_b = AddJob('b', MEDIUM);
+  TestJob* job_c = AddJob('c', HIGHEST);
+  TestJob* job_d = AddJob('d', HIGHEST);
+  TestJob* job_e = AddJob('e', MEDIUM);
+
+  job_a->Finish();
+  job_c->Finish();
+  job_d->Finish();
+  job_b->Finish();
+  job_e->Finish();
+
+  Expect("a.c.d.b.e.");
+}
+
+TEST_F(PrioritizedDispatcherTest, EnforceLimits) {
+  // Reserve 2 for HIGHEST and 1 for LOW or higher.
+  // This leaves 2 for LOWEST or lower.
+  std::vector<size_t> slots(NUM_PRIORITIES);
+  slots[HIGHEST] = 2;
+  slots[LOW] = 1;
+  PrioritizedDispatcher::Limits limits = { 5, slots };
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', IDLE);    // Uses unreserved slot.
+  TestJob* job_b = AddJob('b', IDLE);    // Uses unreserved slot.
+  TestJob* job_c = AddJob('c', LOWEST);  // Must wait.
+  TestJob* job_d = AddJob('d', LOW);     // Uses reserved slot.
+  TestJob* job_e = AddJob('e', MEDIUM);  // Must wait.
+  TestJob* job_f = AddJob('f', HIGHEST); // Uses reserved slot.
+  TestJob* job_g = AddJob('g', HIGHEST); // Uses reserved slot.
+  TestJob* job_h = AddJob('h', HIGHEST); // Must wait.
+
+  EXPECT_EQ(5u, dispatch_->num_running_jobs());
+  EXPECT_EQ(3u, dispatch_->num_queued_jobs());
+
+  job_a->Finish();  // Releases h.
+  job_b->Finish();
+  job_d->Finish();
+  job_f->Finish();  // Releases e.
+  job_g->Finish();
+  job_h->Finish();  // Releases c.
+  job_e->Finish();
+  job_c->Finish();
+
+  Expect("abdfg.h...e..c..");
+}
+
+TEST_F(PrioritizedDispatcherTest, Update) {
+  PrioritizedDispatcher::Limits limits = { 1 };
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', IDLE);
+  TestJob* job_b = AddJob('b', MEDIUM);
+  TestJob* job_c = AddJob('c', HIGHEST);
+  TestJob* job_d = AddJob('d', HIGHEST);
+
+  job_b->Update(HIGHEST);
+  job_c->Update(MEDIUM);
+
+  job_a->Finish();
+  job_d->Finish();
+  job_b->Finish();
+  job_c->Finish();
+
+  Expect("a.d.b.c.");
+}
+
+TEST_F(PrioritizedDispatcherTest, Cancel) {
+  PrioritizedDispatcher::Limits limits = { 1 };
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', IDLE);
+  TestJob* job_b = AddJob('b', IDLE);
+  TestJob* job_c = AddJob('c', IDLE);
+  TestJob* job_d = AddJob('d', IDLE);
+  TestJob* job_e = AddJob('e', IDLE);
+
+  job_b->Cancel();
+  job_d->Cancel();
+
+  job_a->Finish();
+  job_c->Finish();
+  job_e->Finish();
+
+  Expect("a.c.e.");
+}
+
+TEST_F(PrioritizedDispatcherTest, Evict) {
+  PrioritizedDispatcher::Limits limits = { 1 };
+  Prepare(limits);
+
+  TestJob* job_a = AddJob('a', IDLE);
+  TestJob* job_b = AddJob('b', LOW);
+  TestJob* job_c = AddJob('c', HIGHEST);
+  TestJob* job_d = AddJob('d', LOW);
+  TestJob* job_e = AddJob('e', HIGHEST);
+
+  EXPECT_EQ(job_b, dispatch_->EvictOldestLowest());
+  EXPECT_EQ(job_d, dispatch_->EvictOldestLowest());
+
+  job_a->Finish();
+  job_c->Finish();
+  job_e->Finish();
+
+  Expect("a.c.e.");
+}
+
+}  // namespace
+
+}  // namespace net
+