Track the database size on initialization

docs/user/collected-metrics/metrics.md

@@ -128,6 +128,7 @@ The following metrics are added to the ping:
 
 | Name | Type | Description | Data reviews | Extras | Expiration | [Data Sensitivity](https://wiki.mozilla.org/Firefox/Data_Collection) |
 | --- | --- | --- | --- | --- | --- | --- |
+| glean.database.size |[memory_distribution](https://mozilla.github.io/glean/book/user/metrics/memory_distribution.html) |The size of the database file at startup.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1656589)||2020-09-30 | |
 | glean.error.preinit_tasks_overflow |[counter](https://mozilla.github.io/glean/book/user/metrics/counter.html) |The number of tasks queued in the pre-initialization buffer. Only sent if the buffer overflows.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1609482#c3)||never |1 |
 | glean.upload.discarded_exceeding_pings_size |[memory_distribution](https://mozilla.github.io/glean/book/user/metrics/memory_distribution.html) |The size of pings that exceeded the maximum ping size allowed for upload.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1597761#c10)||never |1 |
 | glean.upload.ping_upload_failure |[labeled_counter](https://mozilla.github.io/glean/book/user/metrics/labeled_counters.html) |Counts the number of ping upload failures, by type of failure. This includes failures for all ping types, though the counts appear in the next successfully sent `metrics` ping.  |[1](https://bugzilla.mozilla.org/show_bug.cgi?id=1589124#c1)|<ul><li>status_code_4xx</li><li>status_code_5xx</li><li>status_code_unknown</li><li>unrecoverable</li><li>recoverable</li></ul>|never |1 |

glean-core/metrics.yaml

@@ -391,3 +391,17 @@ glean.upload:
     expires: never
     no_lint:
       - COMMON_PREFIX
+
+glean.database:
+  size:
+    type: memory_distribution
+    description: >
+      The size of the database file at startup.
+    memory_unit: byte
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1656589
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1656589#c7
+    notification_emails:
+      - glean-team@mozilla.com
+    expires: "2020-09-30"

glean-core/src/database/mod.rs

@@ -5,6 +5,8 @@
 use std::collections::btree_map::Entry;
 use std::collections::BTreeMap;
 use std::fs;
+use std::num::NonZeroU64;
+use std::path::Path;
 use std::str;
 use std::sync::RwLock;
 
@@ -32,6 +34,9 @@ pub struct Database {
     /// we will save metrics with 'ping' lifetime data in a map temporarily
     /// so as to persist them to disk using rkv in bulk on demand.
     ping_lifetime_data: Option<RwLock<BTreeMap<String, Metric>>>,
+
+    // Initial file size when opening the database.
+    file_size: Option<NonZeroU64>,
 }
 
 impl std::fmt::Debug for Database {
@@ -46,6 +51,24 @@ impl std::fmt::Debug for Database {
     }
 }
 
+/// Get the file size of a file in the given path and file.
+///
+/// # Arguments
+///
+/// - `path` - The path
+///
+/// # Returns
+///
+/// Returns the non-zero file size in bytes,
+/// or `None` on error or if the size is `0`.
+fn file_size(path: &Path) -> Option<NonZeroU64> {
+    log::trace!("Getting file size for path: {}", path.display());
+    fs::metadata(path)
+        .ok()
+        .map(|stat| stat.len())
+        .and_then(NonZeroU64::new)
+}
+
 impl Database {
     /// Initialize the data store.
     ///
@@ -55,7 +78,12 @@ impl Database {
     /// It also loads any Lifetime::Ping data that might be
     /// persisted, in case `delay_ping_lifetime_io` is set.
     pub fn new(data_path: &str, delay_ping_lifetime_io: bool) -> Result<Self> {
-        let rkv = Self::open_rkv(data_path)?;
+        let path = Path::new(data_path).join("db");
+        log::debug!("Database path: {:?}", path.display());
+
+        let file_size = file_size(&path.join("data.mdb"));
+
+        let rkv = Self::open_rkv(&path)?;
         let user_store = rkv.open_single(Lifetime::User.as_str(), StoreOptions::create())?;
         let ping_store = rkv.open_single(Lifetime::Ping.as_str(), StoreOptions::create())?;
         let application_store =
@@ -72,13 +100,19 @@ impl Database {
             ping_store,
             application_store,
             ping_lifetime_data,
+            file_size,
         };
 
         db.load_ping_lifetime_data();
 
         Ok(db)
     }
 
+    /// Get the initial database file size.
+    pub fn file_size(&self) -> Option<NonZeroU64> {
+        self.file_size
+    }
+
     fn get_store(&self, lifetime: Lifetime) -> &SingleStore {
         match lifetime {
             Lifetime::User => &self.user_store,
@@ -88,9 +122,7 @@ impl Database {
     }
 
     /// Creates the storage directories and inits rkv.
-    fn open_rkv(path: &str) -> Result<Rkv> {
-        let path = std::path::Path::new(path).join("db");
-        log::debug!("Database path: {:?}", path.display());
+    fn open_rkv(path: &Path) -> Result<Rkv> {
         fs::create_dir_all(&path)?;
 
         let rkv = Rkv::new(&path)?;

glean-core/src/internal_metrics.rs

@@ -88,3 +88,26 @@ impl UploadMetrics {
         }
     }
 }
+
+#[derive(Debug)]
+pub struct DatabaseMetrics {
+    pub size: MemoryDistributionMetric,
+}
+
+impl DatabaseMetrics {
+    pub fn new() -> DatabaseMetrics {
+        DatabaseMetrics {
+            size: MemoryDistributionMetric::new(
+                CommonMetricData {
+                    name: "size".into(),
+                    category: "glean.database".into(),
+                    send_in_pings: vec!["metrics".into()],
+                    lifetime: Lifetime::Application,
+                    disabled: false,
+                    dynamic_label: None,
+                },
+                MemoryUnit::Byte,
+            ),
+        }
+    }
+}

glean-core/src/lib.rs

@@ -47,7 +47,7 @@ use crate::debug::DebugOptions;
 pub use crate::error::{Error, ErrorKind, Result};
 pub use crate::error_recording::{test_get_num_recorded_errors, ErrorType};
 use crate::event_database::EventDatabase;
-use crate::internal_metrics::CoreMetrics;
+use crate::internal_metrics::{CoreMetrics, DatabaseMetrics};
 use crate::internal_pings::InternalPings;
 use crate::metrics::{Metric, MetricType, PingType};
 use crate::ping::PingMaker;
@@ -170,6 +170,7 @@ pub struct Glean {
     data_store: Option<Database>,
     event_data_store: EventDatabase,
     core_metrics: CoreMetrics,
+    database_metrics: DatabaseMetrics,
     internal_pings: InternalPings,
     data_path: PathBuf,
     application_id: String,
@@ -210,6 +211,7 @@ impl Glean {
             data_store,
             event_data_store,
             core_metrics: CoreMetrics::new(),
+            database_metrics: DatabaseMetrics::new(),
             internal_pings: InternalPings::new(),
             upload_manager,
             data_path: PathBuf::from(&cfg.data_path),
@@ -318,6 +320,20 @@ impl Glean {
         self.set_application_lifetime_core_metrics();
     }
 
+    /// Initialize the database metrics managed by Glean's Rust core.
+    fn initialize_database_metrics(&mut self) {
+        log::trace!("Initializing database metrics");
+
+        if let Some(size) = self
+            .data_store
+            .as_ref()
+            .and_then(|database| database.file_size())
+        {
+            log::trace!("Database file size: {}", size.get());
+            self.database_metrics.size.accumulate(self, size.get())
+        }
+    }
+
     /// Called when Glean is initialized to the point where it can correctly
     /// assemble pings. Usually called from the language specific layer after all
     /// of the core metrics have been set and the ping types have been
@@ -380,6 +396,7 @@ impl Glean {
     fn on_upload_enabled(&mut self) {
         self.upload_enabled = true;
         self.initialize_core_metrics();
+        self.initialize_database_metrics();
     }
 
     /// Handles the changing of state from upload enabled to disabled.

glean-core/src/lib_unit_tests.rs

@@ -805,3 +805,31 @@ fn test_empty_application_id() {
     // Check that this is indeed the first run.
     assert!(glean.is_first_run());
 }
+
+#[test]
+fn records_database_file_size() {
+    let _ = env_logger::builder().is_test(true).try_init();
+
+    // Note: We don't use `new_glean` because we need to re-use the database directory.
+
+    let dir = tempfile::tempdir().unwrap();
+    let tmpname = dir.path().display().to_string();
+
+    // Initialize Glean once to ensure we create the database.
+    let glean = Glean::with_options(&tmpname, GLOBAL_APPLICATION_ID, true).unwrap();
+    let database_size = &glean.database_metrics.size;
+    let data = database_size.test_get_value(&glean, "metrics");
+    assert!(data.is_none());
+    drop(glean);
+
+    // Initialize Glean again to record file size.
+    let glean = Glean::with_options(&tmpname, GLOBAL_APPLICATION_ID, true).unwrap();
+
+    let database_size = &glean.database_metrics.size;
+    let data = database_size.test_get_value(&glean, "metrics");
+    assert!(data.is_some());
+    let data = data.unwrap();
+
+    // We should see the database containing some data.
+    assert!(data.sum > 0);
+}