Add current metrics

src/Common/CurrentMetrics.cpp

@@ -89,6 +89,9 @@
     M(KafkaConsumersInUse, "Number of consumers which are currently used by direct or background reads") \
     M(KafkaWrites, "Number of currently running inserts to Kafka") \
     M(KafkaAssignedPartitions, "Number of partitions Kafka tables currently assigned to") \
+    M(FilesystemCacheReadBuffers, "Number of active cache buffers") \
+    M(CacheFileSegments, "Number of existing cache file segments") \
+    M(CacheDetachedFileSegments, "Number of existing detached cache file segments") \
 
 namespace CurrentMetrics
 {

src/Common/FileCache.cpp

@@ -284,7 +284,10 @@ void LRUFileCache::fillHolesWithEmptyFileSegments(
         if (fill_with_detached_file_segments)
         {
             auto file_segment = std::make_shared<FileSegment>(current_pos, hole_size, key, this, FileSegment::State::EMPTY);
-            file_segment->detached = true;
+            {
+                std::lock_guard segment_lock(file_segment->mutex);
+                file_segment->markAsDetached(segment_lock);
+            }
             file_segments.insert(it, file_segment);
         }
         else
@@ -308,7 +311,10 @@ void LRUFileCache::fillHolesWithEmptyFileSegments(
         if (fill_with_detached_file_segments)
         {
             auto file_segment = std::make_shared<FileSegment>(current_pos, hole_size, key, this, FileSegment::State::EMPTY);
-            file_segment->detached = true;
+            {
+                std::lock_guard segment_lock(file_segment->mutex);
+                file_segment->markAsDetached(segment_lock);
+            }
             file_segments.insert(file_segments.end(), file_segment);
         }
         else
@@ -364,7 +370,10 @@ FileSegmentsHolder LRUFileCache::get(const Key & key, size_t offset, size_t size
     if (file_segments.empty())
     {
         auto file_segment = std::make_shared<FileSegment>(offset, size, key, this, FileSegment::State::EMPTY);
-        file_segment->detached = true;
+        {
+            std::lock_guard segment_lock(file_segment->mutex);
+            file_segment->markAsDetached(segment_lock);
+        }
         file_segments = { file_segment };
     }
     else

src/Common/FileSegment.cpp

@@ -6,6 +6,11 @@
 #include <IO/Operators.h>
 #include <filesystem>
 
+namespace CurrentMetrics
+{
+extern const Metric CacheDetachedFileSegments;
+}
+
 namespace DB
 {
 
@@ -570,7 +575,7 @@ void FileSegment::completeImpl(std::lock_guard<std::mutex> & cache_lock, std::lo
             cache->reduceSizeToDownloaded(key(), offset(), cache_lock, segment_lock);
         }
 
-        detached = true;
+        markAsDetached(segment_lock);
 
         if (cache_writer)
         {
@@ -685,7 +690,7 @@ void FileSegment::detach(std::lock_guard<std::mutex> & cache_lock, std::lock_gua
     if (detached)
         return;
 
-    detached = true;
+    markAsDetached(segment_lock);
 
     if (!hasFinalizedState())
     {
@@ -693,6 +698,19 @@ void FileSegment::detach(std::lock_guard<std::mutex> & cache_lock, std::lock_gua
     }
 }
 
+void FileSegment::markAsDetached(std::lock_guard<std::mutex> & /* segment_lock */)
+{
+    detached = true;
+    CurrentMetrics::add(CurrentMetrics::CacheDetachedFileSegments);
+}
+
+FileSegment::~FileSegment()
+{
+    std::lock_guard segment_lock(mutex);
+    if (detached)
+        CurrentMetrics::sub(CurrentMetrics::CacheDetachedFileSegments);
+}
+
 FileSegmentsHolder::~FileSegmentsHolder()
 {
     /// In CacheableReadBufferFromRemoteFS file segment's downloader removes file segments from

src/Common/FileSegment.h

@@ -8,6 +8,11 @@
 
 namespace Poco { class Logger; }
 
+namespace CurrentMetrics
+{
+extern const Metric CacheFileSegments;
+}
+
 namespace DB
 {
 
@@ -66,6 +71,8 @@ public:
         size_t offset_, size_t size_, const Key & key_,
         IFileCache * cache_, State download_state_);
 
+    ~FileSegment();
+
     State state() const;
 
     static String stateToString(FileSegment::State state);
@@ -156,7 +163,7 @@ private:
     void assertDetachedStatus(std::lock_guard<std::mutex> & segment_lock) const;
     bool hasFinalizedState() const;
     bool isDetached(std::lock_guard<std::mutex> & /* segment_lock */) const { return detached; }
-
+    void markAsDetached(std::lock_guard<std::mutex> & segment_lock);
 
     void setDownloaded(std::lock_guard<std::mutex> & segment_lock);
     void setDownloadFailed(std::lock_guard<std::mutex> & segment_lock);
@@ -215,6 +222,8 @@ private:
     std::atomic<bool> is_downloaded{false};
     std::atomic<size_t> hits_count = 0; /// cache hits.
     std::atomic<size_t> ref_count = 0; /// Used for getting snapshot state
+
+    CurrentMetrics::Increment metric_increment{CurrentMetrics::CacheFileSegments};
 };
 
 struct FileSegmentsHolder : private boost::noncopyable

src/Disks/IO/CachedReadBufferFromRemoteFS.h

@@ -7,6 +7,12 @@
 #include <Common/logger_useful.h>
 #include <Interpreters/FilesystemCacheLog.h>
 
+
+namespace CurrentMetrics
+{
+extern const Metric FilesystemCacheReadBuffers;
+}
+
 namespace DB
 {
 
@@ -110,6 +116,8 @@ private:
 
     String query_id;
     bool enable_logging = false;
+
+    CurrentMetrics::Increment metric_increment{CurrentMetrics::FilesystemCacheReadBuffers};
 };
 
 }