Update fallback policy for fast fallback. am: 28b45c4f1b am: 596363ef9e

Original change: https://googleplex-android-review.googlesource.com/c/platform/vendor/widevine/+/16096533

Change-Id: Ifd8e70f097345d9d17f2c96e7bdd0415fea62ca5

libwvdrmengine/cdm/core/include/okp_fallback_policy.h

@@ -22,13 +22,14 @@ static constexpr int64_t kSecondsPerDay = kSecondsPerHour * 24;
 // Initial backoff duration.  Subsequent backoff durations for the
 // same engine will double its previous duration.
 static constexpr int64_t kAverageInitialBackoffDuration = kSecondsPerDay;
-static constexpr int64_t kInitalBackoffDurationDelta = kSecondsPerHour * 12;
+static constexpr int64_t kFastBackoffDuration = 30;  // 30 seconds.
+static constexpr int64_t kInitialBackoffDurationDelta = kSecondsPerHour * 12;
 // Minimum backoff duration which an device will be required to
 // backoff the first time.
 static constexpr int64_t kMinInitialBackoffDuration =
-    kAverageInitialBackoffDuration - kInitalBackoffDurationDelta;
+    kAverageInitialBackoffDuration - kInitialBackoffDurationDelta;
 static constexpr int64_t kMaxInitialBackoffDuration =
-    kAverageInitialBackoffDuration + kInitalBackoffDurationDelta;
+    kAverageInitialBackoffDuration + kInitialBackoffDurationDelta;
 
 // SystemFallbackPolicy is a centralized OKP state manager which allows
 // multiple CDM engines to communicate between each other.  In a production
@@ -70,6 +71,9 @@ class SystemFallbackPolicy {
   bool IsProvisioned();
   bool IsInFallbackMode();
 
+  void SetDefaultBackoffDurationRules();
+  void SetFastBackoffDurationRules();
+
   ~SystemFallbackPolicy();
 
  private:
@@ -81,6 +85,8 @@ class SystemFallbackPolicy {
 
   void StoreInfo();
 
+  int64_t GenerateInitialBackoffDuration();
+
   int64_t GetSecondsSinceBackoffStart() const;
   void EndBackoffPeriod();
 
@@ -93,6 +99,10 @@ class SystemFallbackPolicy {
 
   SystemFallbackInfo info_;
 
+  // When |fast_fallback_| is true, falling back only lasts a few
+  // seconds, and exponential backoff is disabled.
+  bool fast_fallback_ = false;
+
   // Handle for the DeviceFiles instance used to store the OKP
   // information.
   // Not set for test instances.

libwvdrmengine/cdm/core/include/okp_info.h

@@ -45,6 +45,7 @@ class SystemFallbackInfo {
     backoff_duration_ = (duration > 0 ? duration : 0);
   }
   void DoubleBackoffDuration() { backoff_duration_ *= 2; }
+  void ClearBackoffDuration() { backoff_duration_ = 0; }
 
   bool HasProvisioningTime() const { return provisioning_time_ != 0; }
   int64_t provisioning_time() const { return provisioning_time_; }