Auto merge of #20320 - kwonoj:feat-wr-revision, r=jdm

feat(capture_webrender): write webrender revision into text

<!-- Please describe your changes on the following line: -->
Relates to #20315 (comment).

This PR try to generate `wr.txt` when trigger webrender capture. By reading gecko's implementation at [here](https://github.com/mozilla/gecko-dev/blob/3b8e63c66ae1989cfc2c7fb48ca9e025a3828e74/gfx/doc/README.webrender#L53), it seems gecko's build script generates txt file for containing revision of webrender and read it each time trigger capturing.

In this PR tries to similar in cruxwise with small differences:
- `cargo build` reads `cargo.lock`, export it into `${OUT_DIR}/`, included via macro in build time.
- when capturing triggered, those revision will be written as `wr.txt`.

Probably point of discussion & need to be updated in PR if necessary:
~- Is it acceptable `mach` generates module file on build bootstrapping? Should there be other recommendation?~ Now cargo build takes care of generation.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #20295 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

- This PR manually verified on local mac OS machine.

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/20320)
<!-- Reviewable:end -->

components/compositing/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.0.1"
 authors = ["The Servo Project Developers"]
 license = "MPL-2.0"
 publish = false
+build = "build.rs"
 
 [lib]
 name = "compositing"
@@ -29,3 +30,6 @@ style_traits = {path = "../style_traits"}
 time = "0.1.17"
 webrender = {git = "https://github.com/servo/webrender", features = ["capture"]}
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
+
+[build-dependencies]
+toml = "0.4.5"

components/compositing/build.rs

@@ -0,0 +1,44 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+extern crate toml;
+
+use std::env;
+use std::fs::File;
+use std::io::{Read, Write};
+use std::path::Path;
+
+fn main() {
+    let lockfile_path = Path::new(&env::var("CARGO_MANIFEST_DIR").unwrap()).join("..").join("..").join("Cargo.lock");
+    let revision_file_path = Path::new(&env::var_os("OUT_DIR").unwrap()).join("webrender_revision.rs");
+
+    let mut lockfile = String::new();
+    File::open(lockfile_path).expect("Cannot open lockfile")
+        .read_to_string(&mut lockfile)
+        .expect("Failed to read lockfile");
+
+    match toml::from_str::<toml::value::Table>(&lockfile) {
+        Ok(result) => {
+            let packages = result.get("package").expect("Cargo lockfile should contain package list");
+
+            match *packages {
+                toml::Value::Array(ref arr) => {
+                    let source = arr
+                        .iter()
+                        .find(|pkg| pkg.get("name").and_then(|name| name.as_str()).unwrap_or("") == "webrender")
+                        .and_then(|pkg| pkg.get("source").and_then(|source| source.as_str()))
+                        .unwrap_or("unknown");
+
+                    let parsed: Vec<&str> = source.split("#").collect();
+                    let revision = if parsed.len() > 1 { parsed[1] } else { source };
+
+                    let mut revision_module_file = File::create(&revision_file_path).unwrap();
+                    write!(&mut revision_module_file, "{}", format!("\"{}\"", revision)).unwrap();
+                },
+                _ => panic!("Cannot find package definitions in lockfile")
+            }
+        },
+        Err(e) => panic!(e)
+    }
+}

components/compositing/compositor.rs

@@ -24,7 +24,8 @@ use servo_config::opts;
 use servo_geometry::{DeviceIndependentPixel, DeviceUintLength};
 use std::collections::HashMap;
 use std::env;
-use std::fs::File;
+use std::fs::{File, create_dir_all};
+use std::io::Write;
 use std::rc::Rc;
 use std::sync::mpsc::Sender;
 use std::time::{Duration, Instant};
@@ -1543,9 +1544,26 @@ impl<Window: WindowMethods> IOCompositor<Window> {
             Ok(current_dir) => {
                 let capture_id = now().to_timespec().sec.to_string();
                 let capture_path = current_dir.join("capture_webrender").join(capture_id);
+                let revision_file_path = capture_path.join("wr.txt");
+
+                if let Err(err) = create_dir_all(&capture_path) {
+                    eprintln!("Unable to create path '{:?}' for capture: {:?}", capture_path, err);
+                    return
+                }
+
                 self.webrender_api.save_capture(capture_path, webrender_api::CaptureBits::all());
+
+                match File::create(revision_file_path) {
+                    Ok(mut file) => {
+                        let revision = include!(concat!(env!("OUT_DIR"), "/webrender_revision.rs"));
+                        if let Err(err) = write!(&mut file, "{}", revision) {
+                            eprintln!("Unable to write webrender revision: {:?}", err)
+                        }
+                    }
+                    Err(err) => eprintln!("Capture triggered, creating webrender revision info skipped: {:?}", err)
+                }
             },
-            Err(err) => println!("could not locate path to save captures: {:?}", err)
+            Err(err) => eprintln!("Unable to locate path to save captures: {:?}", err)
         }
     }
 }