1 files changed, 165 insertions, 0 deletions
diff --git a/libtransport/src/utils/suffix_strategy.h b/libtransport/src/utils/suffix_strategy.h
new file mode 100644
index 000000000..6c4dd2785
--- /dev/null
+++ b/libtransport/src/utils/suffix_strategy.h
@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2017-2019 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <core/manifest_format.h>
+
+namespace utils {
+
+using transport::core::NextSegmentCalculationStrategy;
+
+class SuffixStrategy {
+ public:
+  static constexpr uint32_t INVALID_SUFFIX =
+      std::numeric_limits<uint32_t>::max();
+
+  SuffixStrategy(NextSegmentCalculationStrategy strategy)
+      : suffix_stragegy_(strategy),
+        total_count_(0),
+        final_suffix_(INVALID_SUFFIX) {}
+
+  virtual ~SuffixStrategy() = default;
+
+  virtual uint32_t getNextSuffix() = 0;
+
+  virtual uint32_t getFinalSuffix() { return final_suffix_; }
+
+  virtual void setFinalSuffix(std::uint32_t final_suffix) {
+    if (final_suffix != INVALID_SUFFIX) {
+      final_suffix_ = final_suffix;
+    }
+  }
+
+  virtual uint32_t getNextManifestSuffix() = 0;
+
+  virtual uint32_t getNextContentSuffix() = 0;
+
+  virtual void reset(uint32_t offset = 0) = 0;
+
+  virtual uint32_t getManifestCapacity() = 0;
+
+  virtual void setManifestCapacity(uint32_t capacity) = 0;
+
+  virtual uint32_t getTotalCount() { return total_count_; };
+
+  NextSegmentCalculationStrategy getSuffixStrategy() {
+    return suffix_stragegy_;
+  }
+
+ protected:
+  inline void incrementTotalCount() { total_count_++; };
+
+ protected:
+  NextSegmentCalculationStrategy suffix_stragegy_;
+  std::uint32_t total_count_;
+  std::uint32_t final_suffix_;
+};
+
+class IncrementalSuffixStrategy : public SuffixStrategy {
+ public:
+  IncrementalSuffixStrategy(std::uint32_t start_offset)
+      : SuffixStrategy(NextSegmentCalculationStrategy::INCREMENTAL),
+        next_suffix_(start_offset) {}
+
+  TRANSPORT_ALWAYS_INLINE std::uint32_t getNextSuffix() override {
+    incrementTotalCount();
+    return next_suffix_++;
+  }
+
+  TRANSPORT_ALWAYS_INLINE std::uint32_t getNextContentSuffix() override {
+    return getNextSuffix();
+  }
+
+  TRANSPORT_ALWAYS_INLINE std::uint32_t getNextManifestSuffix() override {
+    return getNextSuffix();
+  }
+
+  uint32_t getManifestCapacity() override {
+    throw errors::RuntimeException(
+        "No manifest capacity in IncrementalSuffixStrategy.");
+  }
+
+  void setManifestCapacity(uint32_t capacity) override {
+    throw errors::RuntimeException(
+        "No manifest capacity in IncrementalSuffixStrategy.");
+  }
+
+  void reset(std::uint32_t offset = 0) override { next_suffix_ = offset; }
+
+ protected:
+  std::uint32_t next_suffix_;
+};
+
+class CapacityBasedSuffixStrategy : public SuffixStrategy {
+ public:
+  CapacityBasedSuffixStrategy(std::uint32_t start_offset,
+                              std::uint32_t manifest_capacity)
+      : SuffixStrategy(NextSegmentCalculationStrategy::INCREMENTAL),
+        next_suffix_(start_offset),
+        segments_in_manifest_(manifest_capacity),
+        current_manifest_iteration_(0) {}
+
+  TRANSPORT_ALWAYS_INLINE std::uint32_t getNextSuffix() override {
+    incrementTotalCount();
+    return next_suffix_++;
+  }
+
+  TRANSPORT_ALWAYS_INLINE std::uint32_t getNextContentSuffix() override {
+    incrementTotalCount();
+    return next_suffix_ % segments_in_manifest_ == 0 ? next_suffix_++
+                                                     : ++next_suffix_;
+  }
+
+  TRANSPORT_ALWAYS_INLINE std::uint32_t getNextManifestSuffix() override {
+    incrementTotalCount();
+    return (current_manifest_iteration_++) * (segments_in_manifest_ + 1);
+  }
+
+  TRANSPORT_ALWAYS_INLINE uint32_t getManifestCapacity() override {
+    return segments_in_manifest_;
+  }
+
+  TRANSPORT_ALWAYS_INLINE void setManifestCapacity(uint32_t capacity) override {
+    segments_in_manifest_ = capacity;
+  }
+
+  void reset(std::uint32_t offset = 0) override { next_suffix_ = offset; }
+
+ protected:
+  std::uint32_t next_suffix_;
+  std::uint32_t segments_in_manifest_;
+  std::uint32_t current_manifest_iteration_;
+};
+
+class SuffixStrategyFactory {
+ public:
+  static std::unique_ptr<SuffixStrategy> getSuffixStrategy(
+      NextSegmentCalculationStrategy strategy, uint32_t start_offset,
+      uint32_t manifest_capacity = 0) {
+    switch (strategy) {
+      case NextSegmentCalculationStrategy::INCREMENTAL:
+        return std::make_unique<IncrementalSuffixStrategy>(start_offset);
+      case NextSegmentCalculationStrategy::MANIFEST_CAPACITY_BASED:
+        return std::make_unique<CapacityBasedSuffixStrategy>(start_offset,
+                                                             manifest_capacity);
+      default:
+        throw errors::RuntimeException(
+            "No valid NextSegmentCalculationStrategy specified.");
+    }
+  }
+};
+
+}  // namespace utils