ring buffer background reader

repertory/librepertory/include/file_manager/ring_buffer_open_file.hpp

@@ -42,8 +42,8 @@ public:
   ring_buffer_open_file() = delete;
   ring_buffer_open_file(const ring_buffer_open_file &) noexcept = delete;
   ring_buffer_open_file(ring_buffer_open_file &&) noexcept = delete;
-  auto operator=(ring_buffer_open_file &&) noexcept -> ring_buffer_open_file & =
-                                                           delete;
+  auto operator=(ring_buffer_open_file &&) noexcept
+      -> ring_buffer_open_file & = delete;
   auto operator=(const ring_buffer_open_file &) noexcept
       -> ring_buffer_open_file & = delete;
 
@@ -64,11 +64,9 @@ private:
   stop_type stop_requested_{false};
 
 private:
-  auto download_chunk(std::size_t chunk) -> api_error;
+  auto download_chunk(std::size_t chunk, bool skip_active) -> api_error;
 
-  void forward_reader_thread(std::size_t count);
-
-  void reverse_reader_thread(std::size_t count);
+  void background_reader_thread();
 
 protected:
   [[nodiscard]] auto is_download_complete() const -> bool override {
@@ -108,8 +106,8 @@ public:
     return false;
   }
 
-  [[nodiscard]] auto
-  native_operation(native_operation_callback callback) -> api_error override;
+  [[nodiscard]] auto native_operation(native_operation_callback callback)
+      -> api_error override;
 
   [[nodiscard]] auto native_operation(std::uint64_t, native_operation_callback)
       -> api_error override {
@@ -129,8 +127,8 @@ public:
 
   void set_api_path(const std::string &api_path) override;
 
-  [[nodiscard]] auto write(std::uint64_t, const data_buffer &,
-                           std::size_t &) -> api_error override {
+  [[nodiscard]] auto write(std::uint64_t, const data_buffer &, std::size_t &)
+      -> api_error override {
     return api_error::not_supported;
   }
 };

repertory/librepertory/include/types/repertory.hpp

@@ -194,6 +194,7 @@ enum class api_error {
   invalid_handle,
   invalid_operation,
   invalid_ring_buffer_multiple,
+  invalid_ring_buffer_position,
   invalid_ring_buffer_size,
   invalid_version,
   item_exists,
@@ -215,31 +216,33 @@ enum class api_error {
 
 [[nodiscard]] auto api_error_from_string(std::string_view str) -> api_error;
 
-[[nodiscard]] auto
-api_error_to_string(const api_error &error) -> const std::string &;
+[[nodiscard]] auto api_error_to_string(const api_error &error)
+    -> const std::string &;
 
 enum class database_type {
   rocksdb,
   sqlite,
 };
-[[nodiscard]] auto database_type_from_string(
-    std::string type,
-    database_type default_type = database_type::rocksdb) -> database_type;
-
 [[nodiscard]] auto
-database_type_to_string(const database_type &type) -> std::string;
+database_type_from_string(std::string type,
+                          database_type default_type = database_type::rocksdb)
+    -> database_type;
+
+[[nodiscard]] auto database_type_to_string(const database_type &type)
+    -> std::string;
 
 enum class download_type {
   direct,
   fallback,
   ring_buffer,
 };
-[[nodiscard]] auto download_type_from_string(
-    std::string type,
-    download_type default_type = download_type::fallback) -> download_type;
-
 [[nodiscard]] auto
-download_type_to_string(const download_type &type) -> std::string;
+download_type_from_string(std::string type,
+                          download_type default_type = download_type::fallback)
+    -> download_type;
+
+[[nodiscard]] auto download_type_to_string(const download_type &type)
+    -> std::string;
 
 enum class exit_code : std::int32_t {
   success = 0,

repertory/librepertory/src/file_manager/ring_buffer_open_file.cpp

@@ -19,6 +19,8 @@
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE.
 */
+#include <algorithm>
+
 #include "file_manager/ring_buffer_open_file.hpp"
 
 #include "app_config.hpp"
@@ -105,22 +107,43 @@ auto ring_buffer_open_file::close() -> bool {
   return open_file_base::close();
 }
 
-auto ring_buffer_open_file::download_chunk(std::size_t chunk) -> api_error {
+auto ring_buffer_open_file::download_chunk(std::size_t chunk, bool skip_active)
+    -> api_error {
   unique_mutex_lock chunk_lock(chunk_mtx_);
-  if (active_downloads_.find(chunk) != active_downloads_.end()) {
-    auto active_download = active_downloads_.at(chunk);
+  const auto unlock_and_notify = [this, &chunk_lock]() {
     chunk_notify_.notify_all();
     chunk_lock.unlock();
+  };
+
+  const auto unlock_and_return =
+      [&unlock_and_notify](api_error res) -> api_error {
+    unlock_and_notify();
+    return res;
+  };
+
+  if (chunk < ring_begin_ || chunk > ring_end_) {
+    return unlock_and_return(api_error::invalid_ring_buffer_position);
+  }
+
+  if (active_downloads_.find(chunk) != active_downloads_.end()) {
+    if (skip_active) {
+      return unlock_and_return(api_error::success);
+    }
+
+    auto active_download = active_downloads_.at(chunk);
+    unlock_and_notify();
 
     return active_download->wait();
   }
 
-  if (ring_state_[chunk % ring_state_.size()]) {
+  if (not ring_state_[chunk % ring_state_.size()]) {
+    return unlock_and_return(api_error::success);
+  }
+
   auto active_download{std::make_shared<download>()};
   active_downloads_[chunk] = active_download;
   ring_state_[chunk % ring_state_.size()] = false;
-    chunk_notify_.notify_all();
-    chunk_lock.unlock();
+  unlock_and_notify();
 
   data_buffer buffer;
   auto data_offset{chunk * chunk_size_};
@@ -132,32 +155,30 @@ auto ring_buffer_open_file::download_chunk(std::size_t chunk) -> api_error {
       provider_.read_file_bytes(fsi_.api_path, data_size, data_offset, buffer,
                                 stop_requested_),
   };
+
+  chunk_lock.lock();
   if (res == api_error::success) {
-      res = do_io([&]() -> api_error {
+    res = (chunk >= ring_begin_ && chunk <= ring_end_)
+              ? do_io([&]() -> api_error {
                   std::size_t bytes_written{};
-        if (nf_->write(buffer, (chunk % ring_state_.size()) * chunk_size_,
+                  if (nf_->write(buffer,
+                                 (chunk % ring_state_.size()) * chunk_size_,
                                  &bytes_written)) {
                     return api_error::success;
                   }
 
                   return api_error::os_error;
-      });
+                })
+              : api_error::invalid_ring_buffer_position;
   }
 
+  active_downloads_.erase(chunk);
+  unlock_and_notify();
+
   active_download->notify(res);
-
-    chunk_lock.lock();
-    active_downloads_.erase(chunk);
-    chunk_notify_.notify_all();
   return res;
 }
 
-  chunk_notify_.notify_all();
-  chunk_lock.unlock();
-
-  return api_error::success;
-}
-
 void ring_buffer_open_file::forward(std::size_t count) {
   mutex_lock chunk_lock(chunk_mtx_);
   if ((ring_pos_ + count) > (total_chunks_ - 1U)) {
@@ -179,6 +200,7 @@ void ring_buffer_open_file::forward(std::size_t count) {
       ring_begin_ += added;
       ring_pos_ += count;
     }
+
     ring_end_ =
         std::min(total_chunks_ - 1U, ring_begin_ + ring_state_.size() - 1U);
   }
@@ -204,9 +226,7 @@ auto ring_buffer_open_file::native_operation(
 
 void ring_buffer_open_file::reverse(std::size_t count) {
   mutex_lock chunk_lock(chunk_mtx_);
-  if (ring_pos_ < count) {
-    count = ring_pos_;
-  }
+  count = std::min(ring_pos_, count);
 
   if ((ring_pos_ - count) >= ring_begin_) {
     ring_pos_ -= count;
@@ -232,16 +252,14 @@ void ring_buffer_open_file::reverse(std::size_t count) {
 }
 
 auto ring_buffer_open_file::read(std::size_t read_size,
-                                 std::uint64_t read_offset,
-                                 data_buffer &data) -> api_error {
+                                 std::uint64_t read_offset, data_buffer &data)
+    -> api_error {
   if (fsi_.directory) {
     return api_error::invalid_operation;
   }
 
   reset_timeout();
 
-  mutex_lock lock(read_mtx_);
-
   read_size = utils::calculate_read_size(fsi_.size, read_size, read_offset);
   if (read_size == 0U) {
     return api_error::success;
@@ -251,6 +269,8 @@ auto ring_buffer_open_file::read(std::size_t read_size,
   read_offset = read_offset - (begin_chunk * chunk_size_);
 
   auto res{api_error::success};
+
+  unique_mutex_lock read_lock(read_mtx_);
   for (std::size_t chunk = begin_chunk;
        (res == api_error::success) && (read_size > 0U); ++chunk) {
     if (chunk > ring_pos_) {
@@ -259,10 +279,16 @@ auto ring_buffer_open_file::read(std::size_t read_size,
       reverse(ring_pos_ - chunk);
     }
 
-    reset_timeout();
-
-    res = download_chunk(chunk);
+    res = download_chunk(chunk, false);
     if (res != api_error::success) {
+      if (not stop_requested_ &&
+          res == api_error::invalid_ring_buffer_position) {
+        read_lock.unlock();
+
+        // TODO limit retry
+        return read(read_size, read_offset, data);
+      }
+
       return res;
     }
 
@@ -331,4 +357,29 @@ void ring_buffer_open_file::set_api_path(const std::string &api_path) {
   open_file_base::set_api_path(api_path);
   chunk_notify_.notify_all();
 }
+
+void ring_buffer_open_file::background_reader_thread() {
+  unique_mutex_lock read_lock(read_mtx_);
+  read_lock.unlock();
+
+  while (not stop_requested_) {
+    read_lock.lock();
+    auto next_chunk =
+        ring_pos_ + 1U >= ring_state_.size() ? 0U : ring_pos_ + 1U;
+    if (not ring_state_[next_chunk % ring_state_.size()]) {
+      read_lock.unlock();
+      continue;
+    }
+
+    read_lock.unlock();
+    download_chunk(next_chunk, true);
+
+    unique_mutex_lock chunk_lock(chunk_mtx_);
+    if (ring_state_.none()) {
+      chunk_notify_.wait(chunk_lock);
+    }
+
+    chunk_notify_.notify_all();
+  }
+}
 } // namespace repertory

repertory/librepertory/src/types/repertory.cpp

@@ -25,8 +25,8 @@
 #include "utils/string.hpp"
 
 namespace repertory {
-auto database_type_from_string(std::string type,
-                               database_type default_type) -> database_type {
+auto database_type_from_string(std::string type, database_type default_type)
+    -> database_type {
   type = utils::string::to_lower(utils::string::trim(type));
   if (type == "rocksdb") {
     return database_type::rocksdb;
@@ -50,8 +50,8 @@ auto database_type_to_string(const database_type &type) -> std::string {
   }
 }
 
-auto download_type_from_string(std::string type,
-                               download_type default_type) -> download_type {
+auto download_type_from_string(std::string type, download_type default_type)
+    -> download_type {
   type = utils::string::to_lower(utils::string::trim(type));
   if (type == "direct") {
     return download_type::direct;
@@ -106,6 +106,7 @@ static const std::unordered_map<api_error, std::string> LOOKUP = {
     {api_error::invalid_handle, "invalid_handle"},
     {api_error::invalid_operation, "invalid_operation"},
     {api_error::invalid_ring_buffer_multiple, "invalid_ring_buffer_multiple"},
+    {api_error::invalid_ring_buffer_position, "invalid_ring_buffer_position"},
     {api_error::invalid_ring_buffer_size, "invalid_ring_buffer_size"},
     {api_error::invalid_version, "invalid_version"},
     {api_error::item_exists, "item_exists"},