Add initialization check and waiting duration for filesystem access

Author: dhebbeker

lib/board_adapters/storage/storage.cpp

@@ -32,16 +32,24 @@ static std::atomic<bool> requestFileSystemActive;
 static std::thread stateMachine;
 static std::mutex fileSystemState_mutex; //!< used to lock the actual state
 static bool fileSystemIsActive;          //!< describes the current state
+static bool storageIsInitialized = false;
 
-std::shared_ptr<fs::FS> Storage::getFileSystem_locking()
+std::optional<std::shared_ptr<fs::FS>> Storage::getFileSystem_locking(const std::chrono::milliseconds rel_time)
 {
+    if (!storageIsInitialized)
+    {
+        return std::nullopt;
+    }
     std::unique_lock fs_state_lock{fileSystemState_mutex};
     if (!fileSystemIsActive)
     {
-        stateChanged.wait(fs_state_lock, []() { return fileSystemIsActive; });
+        if (!stateChanged.wait_for(fs_state_lock, rel_time, []() { return fileSystemIsActive; }))
+        {
+            return std::nullopt;
+        }
     }
     fs_state_lock.release();
-    return {&FFat, [](fs::FS *) { fileSystemState_mutex.unlock(); }};
+    return std::shared_ptr<fs::FS>{&FFat, [](fs::FS *) { fileSystemState_mutex.unlock(); }};
 }
 
 static void requestState(const bool fileSystemActive)
@@ -116,8 +124,12 @@ static bool usbMsc_onStartStop(const std::uint8_t power_condition, const bool st
     return true;
 }
 
-std::size_t Storage::size()
+std::optional<std::size_t> Storage::size()
 {
+    if (!storageIsInitialized)
+    {
+        return std::nullopt;
+    }
     return FFat.totalBytes();
 }
 
@@ -137,21 +149,20 @@ static void usbStartedCallback(void *, esp_event_base_t, int32_t, void *)
     requestState(false);
 }
 
-void Storage::begin()
+bool Storage::begin()
 {
-
     if (!FFat.begin(true))
     {
         ESP_LOGE(TAG, "Failed to init files system, flash may not be formatted");
-        return;
+        return storageIsInitialized = false;
     }
     ESP_LOGI(TAG, "file system initialized");
 
     partition = check_ffat_partition(FFAT_PARTITION_LABEL);
     if (!partition)
     {
         ESP_LOGE(TAG, "Error with FAT partition");
-        return;
+        return storageIsInitialized = false;
     }
     ESP_LOGI(TAG, "Flash has a size of %u bytes\n", FFat.totalBytes());
 
@@ -175,11 +186,14 @@ void Storage::begin()
     if (!usbMsc.begin(FFat.totalBytes() / blockSize, blockSize))
     {
         ESP_LOGE(TAG, "starting USB MSC failed");
+        return storageIsInitialized = false;
     }
     if (!USB.begin())
     {
         ESP_LOGE(TAG, "starting USB failed");
+        return storageIsInitialized = false;
     }
+    return storageIsInitialized = true;
 }
 
 void Storage::end()

lib/board_adapters/storage/storage.hpp

@@ -1,6 +1,8 @@
 #pragma once
+#include <chrono>
 #include <cstddef>
 #include <memory>
+#include <optional>
 
 namespace fs
 {
@@ -34,8 +36,9 @@ struct Storage
      * 
      * @post storage may be used afterwards
      * @warning do not call again unless end() was called after before
+     * @retval true in case initialization was successful
      */
-    static void begin();
+    static bool begin();
 
     /**
      * @brief Disengages filesystem and USB
@@ -46,15 +49,16 @@ struct Storage
      * @brief Get locking access to filesystem.
      * 
      * @pre storage must be initialized first
+     * @param maxWaiting maximum time to wait for a USB host device to release access
      * @return smart pointer, locking storage to filesystem until deleted
      */
-    static std::shared_ptr<fs::FS> getFileSystem_locking();
+    static std::optional<std::shared_ptr<fs::FS>> getFileSystem_locking(std::chrono::milliseconds maxWaiting = std::chrono::milliseconds::max());
 
     /**
      * @brief Gets the total size of memory.
      * 
      * @pre storage must be initialized first
-     * @return size in bytes
+     * @return size in bytes if storage is initialized
      */
-    static std::size_t size();
+    static std::optional<std::size_t> size();
 };

src/main.cpp

@@ -3,6 +3,7 @@
  */
 
 #include <FS.h>
+#include <cassert>
 #include <chrono>
 #include <esp32-hal-log.h>
 #include <esp_err.h>
@@ -71,7 +72,7 @@ void setup()
     ESP_LOGI(TAG, "Example info");
     ESP_LOGD(TAG, "Example debug");
     ESP_LOGV(TAG, "Example verbose");
-    Storage::begin();
+    assert(Storage::begin());
 }
 
 void loop()
@@ -88,6 +89,10 @@ void loop()
 
     presenter.loop();
 
-    listFiles("/", Storage::getFileSystem_locking());
+    const auto fileSystemHandle = Storage::getFileSystem_locking(3s);
+    if (fileSystemHandle)
+    {
+        listFiles("/", fileSystemHandle.value());
+    }
     std::this_thread::sleep_for(3s);
 }