mu-indexer: clean up state management

lib/index/mu-indexer.cc

@@ -40,6 +40,29 @@ using namespace std::chrono_literals;
 
 using namespace Mu;
 
+struct IndexState {
+        enum State { Idle, Scanning, Cleaning };
+        static const char* name(State s) {
+                switch(s) {
+                case Idle:     return "idle";
+                case Scanning: return "scanning";
+                case Cleaning: return "cleaning";
+                default:       return "<error>";
+                }
+        }
+
+        bool operator==(State rhs) const { return state_ == rhs; }
+
+        void change_to(State new_state) {
+                g_debug ("changing indexer state %s->%s",
+                         name((State)state_), name((State)new_state));
+                state_ = new_state;
+        }
+
+private:
+        State state_{Idle};
+};
+
 struct Indexer::Private {
         Private (Mu::Store& store):
                 store_{store},
@@ -73,24 +96,15 @@ struct Indexer::Private {
         Scanner         scanner_;
         const size_t    max_message_size_;
 
-        time_t                dirstamp_{};
-        std::atomic<bool>     scan_done_{true}, clean_done_{true};
-
+        time_t                   dirstamp_{};
         std::size_t              max_workers_;
         std::vector<std::thread> workers_;
         std::thread              scanner_worker_;
 
         AsyncQueue<std::string> fq_;
 
-        struct Progress {
-                void reset() {
-                        processed = updated = removed = 0;
-                }
-                std::atomic<size_t> processed{};  /**< Number of messages processed */
-                std::atomic<size_t> updated{};   /**< Number of messages added/updated to store */
-                std::atomic<size_t> removed{};   /**< Number of message removed from store */
-        };
-        Progress progress_;
+        Progress   progress_;
+        IndexState state_;
 
         std::mutex lock_, wlock_;
 };
@@ -178,7 +192,7 @@ Indexer::Private::worker()
 
         g_debug ("started worker");
 
-        while (!scan_done_ || !fq_.empty()) {
+        while (state_ == IndexState::Scanning || !fq_.empty()) {
 
                 if (!fq_.pop (item, 250ms))
                         continue;
@@ -204,28 +218,23 @@ Indexer::Private::cleanup()
 {
         g_debug ("starting cleanup");
 
-        std::vector<Store::Id> orphans_; // store messages without files.
+        size_t n{};
+        std::vector<Store::Id> orphans; // store messages without files.
         store_.for_each_message_path([&](Store::Id id, const std::string &path) {
 
-                if (clean_done_)
-                        return false;
-
-                if (::access(path.c_str(), F_OK) != 0) {
-                        g_debug ("%s not found; queueing id=%u for removal",
+                ++n;
+                if (::access(path.c_str(), R_OK) != 0) {
+                        g_debug ("cannot read %s (id=%u); queueing for removal from store",
                                  path.c_str(), id);
-                        orphans_.emplace_back(id);
+                        orphans.emplace_back(id);
                 }
 
-                return !clean_done_;
+                return state_ == IndexState::Cleaning;
         });
 
-        if (orphans_.empty()) {
-                g_debug("nothing to clean up");
-                return true;
-        }
+        g_debug("remove %zu message(s) from store", orphans.size());
 
-        store_.remove_messages (orphans_);
-        g_debug ("removed %zu orphan messages from store", orphans_.size());
+        store_.remove_messages (orphans);
 
         return true;
 }
@@ -242,40 +251,36 @@ Indexer::Private::start(const Indexer::Config& conf)
         else
                 max_workers_ = conf.max_threads;
 
-        g_debug ("starting indexer with up to %zu worker threads", max_workers_);
+        g_debug ("starting indexer with <= %zu worker thread(s)", max_workers_);
+        g_debug ("indexing: %s; clean-up: %s",
+                 conf_.scan ? "yes" : "no",
+                 conf_.cleanup ? "yes" : "no");
 
-        scan_done_ = false;
         workers_.emplace_back(std::thread([this]{worker();}));
 
-        scan_done_      = clean_done_ = false;
+        state_.change_to(IndexState::Scanning);
         scanner_worker_ = std::thread([this]{
-
-                progress_.reset();
+                progress_ = {};
 
                 if (conf_.scan) {
                         g_debug("starting scanner");
-
-                        const auto started{scanner_.start()};
-                        clean_done_ = scan_done_ = true; // so listeners will stop.
-
-                        if (!started) {
+                        if (!scanner_.start()) { // blocks.
                                 g_warning ("failed to start scanner");
-                                return;
-                        } else
-                                g_debug ("scanner finished");
+                                goto leave;
+                        }
+                        g_debug ("scanner finished");
                 }
 
                 if (conf_.cleanup) {
                         g_debug ("starting cleanup");
+                        state_.change_to(IndexState::Cleaning);
                         cleanup();
-                        clean_done_ = true;
                         g_debug ("cleanup finished");
-                } else {
-                        clean_done_ = true;
-                        g_debug ("cleanup skipped");
                 }
 
                 store_.commit();
+                leave:
+                state_.change_to(IndexState::Idle);
         });
 
         g_debug ("started indexer");
@@ -287,7 +292,7 @@ bool
 Indexer::Private::stop()
 {
         scanner_.stop();
-        scan_done_ = clean_done_ = true;
+        state_.change_to(IndexState::Idle);
 
         const auto w_n = workers_.size();
 
@@ -343,17 +348,14 @@ Indexer::stop()
 bool
 Indexer::is_running() const
 {
-        return !priv_->scan_done_ || !priv_->clean_done_ ||
-                !priv_->fq_.empty();
+        return !(priv_->state_ == IndexState::Idle) || !priv_->fq_.empty();
 }
 
 Indexer::Progress
 Indexer::progress() const
 {
-        return Progress{
-                is_running(),
-                priv_->progress_.processed,
-                priv_->progress_.updated,
-                priv_->progress_.removed
-        };
+        priv_->progress_.running =
+                priv_->state_ == IndexState::Idle ? false : true;
+
+        return priv_->progress_;
 }

lib/index/mu-indexer.hh

@@ -50,9 +50,9 @@ public:
                 /**< clean messages no longer in the file system */
                 size_t max_threads{};
                 /**< maximum # of threads to use */
-                bool   ignore_noupdate{};
+                bool ignore_noupdate{};
                 /**< ignore .noupdate files */
-                bool   lazy_check{};
+                bool lazy_check{};
                 /**< whether to skip directories that don't have a changed
                  * mtime */
         };