Bug 1632131 - Implement a string metric for the in-tree Glean API. r=chutten

Currently there's no user, so we do some trickery to actually make sure
it gets compiled.

It also lacks a test, that will follow in the next commit,
as it's a bit more complex to set up a Glean instance for a test run.

Differential Revision: https://phabricator.services.mozilla.com/D72128

Cargo.lock

@@ -1413,6 +1413,7 @@ checksum = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 name = "fog"
 version = "0.1.0"
 dependencies = [
+ "glean",
  "glean-core",
  "log",
  "nserror",
@@ -1810,6 +1811,14 @@ dependencies = [
  "gl_generator",
 ]
 
+[[package]]
+name = "glean"
+version = "0.1.0"
+dependencies = [
+ "glean-core",
+ "log",
+]
+
 [[package]]
 name = "glean-core"
 version = "25.1.0"

toolkit/components/glean/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "fog"
 version = "0.1.0"
-authors = ["The Mozilla Project Developers"]
+authors = ["Glean SDK team <glean-team@mozilla.com>"]
 edition = "2018"
 license = "MPL-2.0"
 
@@ -13,3 +13,4 @@ nsstring = { path = "../../../xpcom/rust/nsstring" }
 static_prefs = { path = "../../../modules/libpref/init/static_prefs" }
 xpcom = { path = "../../../xpcom/rust/xpcom" }
 once_cell = "1.2.0"
+glean = { path = "./api" }

toolkit/components/glean/api/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "glean"
+version = "0.1.0"
+authors = ["Glean SDK team <glean-team@mozilla.com>"]
+edition = "2018"
+publish = false
+
+[dependencies]
+glean-core = "25.1.0"
+log = "0.4"

toolkit/components/glean/api/src/lib.rs

@@ -0,0 +1,29 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+//! The public Glean SDK API, for Rust consumers.
+//!
+//! ## Example:
+//!
+//! ```rust,ignore
+//! assert!(glean::is_upload_enabled())
+//! ```
+
+pub mod metrics;
+
+/// Run a closure with a mutable reference to the locked global Glean object.
+fn with_glean<F, R>(f: F) -> R
+where
+    F: FnOnce(&glean_core::Glean) -> R,
+{
+    let lock = glean_core::global_glean().lock().unwrap();
+    f(&lock)
+}
+
+/// Determine whether upload is enabled.
+///
+/// See `glean_core::Glean.is_upload_enabled`.
+pub fn is_upload_enabled() -> bool {
+    with_glean(|glean| glean.is_upload_enabled())
+}

toolkit/components/glean/api/src/metrics/mod.rs

@@ -0,0 +1,14 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+//! The different metric types supported by the Glean SDK to handle data.
+
+// Re-export of `glean_core` types we can re-use.
+// That way a user only needs to depend on this crate, not on glean_core (and there can't be a
+// version mismatch).
+pub use glean_core::{CommonMetricData, Lifetime};
+
+mod string;
+
+pub use string::StringMetric;

toolkit/components/glean/api/src/metrics/string.rs

@@ -0,0 +1,67 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+use glean_core::CommonMetricData;
+
+/// A string metric.
+///
+/// Record an Unicode string value with arbitrary content.
+/// Strings are length-limited to `MAX_LENGTH_VALUE` bytes.
+///
+/// # Example
+///
+/// The following piece of code will be generated by `glean_parser`:
+///
+/// ```rust,ignore
+/// use glean::metrics::{StringMetric, CommonMetricData, Lifetime};
+/// use once_cell::sync::Lazy;
+///
+/// mod browser {
+///     pub static search_engine: Lazy<StringMetric> = Lazy::new(|| StringMetric::new(CommonMetricData {
+///         name: "search_engine".into(),
+///         category: "browser".into(),
+///         lifetime: Lifetime::Ping,
+///         disabled: false,
+///         dynamic_label: None
+///     }));
+/// }
+/// ```
+///
+/// It can then be used with:
+///
+/// ```rust,ignore
+/// browser::search_engine.set("websearch");
+/// ```
+#[derive(Clone, Debug)]
+pub struct StringMetric(glean_core::metrics::StringMetric);
+
+impl StringMetric {
+    /// Create a new string metric.
+    pub fn new(meta: CommonMetricData) -> Self {
+        Self(glean_core::metrics::StringMetric::new(meta))
+    }
+
+    /// Set to the specified value.
+    ///
+    /// ## Arguments
+    ///
+    /// * `value` - The string to set the metric to.
+    ///
+    /// ## Notes
+    ///
+    /// Truncates the value if it is longer than `MAX_STRING_LENGTH` bytes and logs an error.
+    /// See [String metric limits](https://mozilla.github.io/glean/book/user/metrics/string.html#limits).
+    pub fn set<S: Into<String>>(&self, value: S) {
+        crate::with_glean(move |glean| self.0.set(glean, value))
+    }
+
+    /// **Test-only API.**
+    ///
+    /// Get the currently stored value as a string.
+    ///
+    /// This doesn't clear the stored value.
+    pub fn test_get_value(&self, storage_name: &str) -> Option<String> {
+        crate::with_glean(move |glean| self.0.test_get_value(glean, storage_name))
+    }
+}

toolkit/components/glean/src/api.rs

@@ -98,7 +98,9 @@ fn initialize_core_metrics(glean: &Glean, client_info: &ClientInfo) {
     core_metrics
         .os_version
         .set(glean, &client_info.os_version[..]);
-    core_metrics.architecture.set(glean, &client_info.architecture);
+    core_metrics
+        .architecture
+        .set(glean, &client_info.architecture);
     // FIXME(bug 1625207): Device manufacturer should be made optional.
     core_metrics
         .device_manufacturer

toolkit/components/glean/src/lib.rs

@@ -17,6 +17,10 @@
 //! [privacy-policy]: https://www.mozilla.org/privacy/
 //! [docs]: https://firefox-source-docs.mozilla.org/toolkit/components/glean/
 
+// No one is currently using the Glean SDK, so let's export it, so we know it gets
+// compiled.
+pub extern crate glean;
+
 use std::ffi::CStr;
 use std::os::raw::c_char;
 
@@ -41,7 +45,7 @@ pub unsafe extern "C" fn fog_init(
     app_display_version: &nsACString,
     channel: *const c_char,
     os_version: &nsACString,
-    architecture: &nsACString
+    architecture: &nsACString,
 ) -> nsresult {
     log::debug!("Initializing FOG.");