Add SQLite page_count and file_size metrics

src/storage/backend/sqlite/SQLite.cc

@@ -2,6 +2,7 @@
 
 #include "zeek/storage/backend/sqlite/SQLite.h"
 
+#include <sys/stat.h>
 #include <filesystem>
 #include <thread>
 
@@ -12,7 +13,7 @@
 #include "zeek/Func.h"
 #include "zeek/Val.h"
 #include "zeek/storage/ReturnCode.h"
-#include "zeek/telemetry/Counter.h"
+#include "zeek/telemetry/Manager.h"
 
 #include "const.bif.netvar_h"
 
@@ -260,6 +261,33 @@ OperationResult SQLite::DoOpen(OpenResultCallback* cb, RecordValPtr options) {
     get_expiry_last_run_stmt = std::move(stmt_ptrs[6]);
     update_expiry_last_run_stmt = std::move(stmt_ptrs[7]);
 
+    page_count_metric =
+        telemetry_mgr->GaugeInstance("zeek", "storage_sqlite_database_size", {{"config", GetConfigMetricsLabel()}},
+                                     "Storage sqlite backend value of page_count pragma", "pages", [this]() {
+                                         static auto double_parser = [](sqlite3_stmt* stmt) -> OperationResult {
+                                             double val = sqlite3_column_double(stmt, 0);
+                                             return {ReturnCode::SUCCESS, "", make_intrusive<DoubleVal>(val)};
+                                         };
+
+                                         auto res = RunPragma("page_count", std::nullopt, double_parser);
+                                         if ( res.code == ReturnCode::SUCCESS ) {
+                                             last_page_count_value = cast_intrusive<DoubleVal>(res.value)->Get();
+                                         }
+
+                                         return last_page_count_value;
+                                     });
+
+    file_size_metric =
+        telemetry_mgr->GaugeInstance("zeek", "storage_sqlite_database_size", {{"config", GetConfigMetricsLabel()}},
+                                     "Storage sqlite backend database file size on disk", "bytes", [this]() {
+                                         struct stat s{0};
+                                         if ( int ret = stat(full_path.c_str(), &s); ret == 0 ) {
+                                             last_file_size_value = static_cast<double>(s.st_size);
+                                         }
+
+                                         return last_file_size_value;
+                                     });
+
     return {ReturnCode::SUCCESS};
 }
 
@@ -306,6 +334,12 @@ OperationResult SQLite::DoClose(ResultCallback* cb) {
         expire_db = nullptr;
     }
 
+    if ( page_count_metric )
+        page_count_metric->RemoveCallback();
+
+    if ( file_size_metric )
+        file_size_metric->RemoveCallback();
+
     return op_res;
 }
 

src/storage/backend/sqlite/SQLite.h

@@ -76,6 +76,12 @@ private:
     std::string table_name;
     std::chrono::milliseconds pragma_timeout;
     std::chrono::milliseconds pragma_wait_on_busy;
+
+    telemetry::GaugePtr page_count_metric;
+    telemetry::GaugePtr file_size_metric;
+
+    double last_page_count_value = 0.0;
+    double last_file_size_value = 0.0;
 };
 
 } // namespace zeek::storage::backend::sqlite

src/telemetry/Counter.h

@@ -62,6 +62,7 @@ public:
 
     bool HasCallback() const noexcept { return callback != nullptr; }
     double RunCallback() const { return callback(); }
+    void RemoveCallback() { callback = nullptr; }
 
 private:
     friend class CounterFamily;

src/telemetry/Gauge.h

@@ -84,6 +84,7 @@ public:
 
     bool HasCallback() const noexcept { return callback != nullptr; }
     double RunCallback() const { return callback(); }
+    void RemoveCallback() { callback = nullptr; }
 
 private:
     FamilyType* family = nullptr;

testing/btest/Baseline/scripts.base.frameworks.storage.sqlite-basic/out

@@ -12,6 +12,8 @@ get result same as inserted, T
 
 Post-operation metrics:
 Telemetry::COUNTER, zeek, zeek_storage_backends_opened_total, [], [], 1.0
+Telemetry::GAUGE, zeek, zeek_storage_sqlite_database_size_bytes, [config], [test.sqlite-testing], 4096.0
+Telemetry::GAUGE, zeek, zeek_storage_sqlite_database_size_pages, [config], [test.sqlite-testing], 5.0
 Telemetry::COUNTER, zeek, zeek_storage_backend_data_read_bytes_total, [config, type], [test.sqlite-testing, Storage::STORAGE_BACKEND_SQLITE], 18.0
 Telemetry::COUNTER, zeek, zeek_storage_backend_expired_entries_total, [config, type], [test.sqlite-testing, Storage::STORAGE_BACKEND_SQLITE], 0.0
 Telemetry::COUNTER, zeek, zeek_storage_backend_operation_results_total, [config, operation, result, type], [test.sqlite-testing, erase, error, Storage::STORAGE_BACKEND_SQLITE], 0.0

testing/btest/Baseline/scripts.base.frameworks.storage.sqlite-metrics/out

@@ -7,6 +7,8 @@ get result 2, [code=Storage::KEY_NOT_FOUND, error_str=<uninitialized>, value=<un
 
 Post-operation metrics:
 Telemetry::COUNTER, zeek, zeek_storage_backends_opened_total, [], [], 1.0
+Telemetry::GAUGE, zeek, zeek_storage_sqlite_database_size_bytes, [config], [test.sqlite-testing], 4096.0
+Telemetry::GAUGE, zeek, zeek_storage_sqlite_database_size_pages, [config], [test.sqlite-testing], 5.0
 Telemetry::COUNTER, zeek, zeek_storage_backend_data_read_bytes_total, [config, type], [test.sqlite-testing, Storage::STORAGE_BACKEND_SQLITE], 18.0
 Telemetry::COUNTER, zeek, zeek_storage_backend_expired_entries_total, [config, type], [test.sqlite-testing, Storage::STORAGE_BACKEND_SQLITE], 0.0
 Telemetry::COUNTER, zeek, zeek_storage_backend_operation_results_total, [config, operation, result, type], [test.sqlite-testing, erase, error, Storage::STORAGE_BACKEND_SQLITE], 0.0