# Objective
[Tracy](https://github.com/wolfpld/tracy) is:
> A real time, nanosecond resolution, remote telemetry, hybrid frame and sampling profiler for games and other applications.
With the `trace_tracy` feature enabled, you run your bevy app and either a headless server (`capture`) or a live, interactive profiler UI (`Tracy`), and connect that to your bevy application to then stream the metric data and events, and save it or inspect it live/offline.
Previously when I implemented the spans across systems and stages and I was trying out different profiling tools, Tracy was too unstable on macOS to use. But now, quite some months later, it is working stably with Tracy 0.7.8. You can see timelines, aggregate statistics of mean system/stage execution times, and much more. It's very useful!
## Solution
- Use the `tracing-tracy` crate which supports our tracing spans
- Expose via the non-default feature `trace_tracy` for consistency with other `trace*` features
This relicenses Bevy under the dual MIT or Apache-2.0 license. For rationale, see #2373.
* Changes the LICENSE file to describe the dual license. Moved the MIT license to docs/LICENSE-MIT. Added the Apache-2.0 license to docs/LICENSE-APACHE. I opted for this approach over dumping both license files at the root (the more common approach) for a number of reasons:
* Github links to the "first" license file (LICENSE-APACHE) in its license links (you can see this in the wgpu and rust-analyzer repos). People clicking these links might erroneously think that the apache license is the only option. Rust and Amethyst both use COPYRIGHT or COPYING files to solve this problem, but this creates more file noise (if you do everything at the root) and the naming feels way less intuitive.
* People have a reflex to look for a LICENSE file. By providing a single license file at the root, we make it easy for them to understand our licensing approach.
* I like keeping the root clean and noise free
* There is precedent for putting the apache and mit license text in sub folders (amethyst)
* Removed the `Copyright (c) 2020 Carter Anderson` copyright notice from the MIT license. I don't care about this attribution, it might make license compliance more difficult in some cases, and it didn't properly attribute other contributors. We shoudn't replace it with something like "Copyright (c) 2021 Bevy Contributors" because "Bevy Contributors" is not a legal entity. Instead, we just won't include the copyright line (which has precedent ... Rust also uses this approach).
* Updates crates to use the new "MIT OR Apache-2.0" license value
* Removes the old legion-transform license file from bevy_transform. bevy_transform has been its own, fully custom implementation for a long time and that license no longer applies.
* Added a License section to the main readme
* Updated our Bevy Plugin licensing guidelines.
As a follow-up we should update the website to properly describe the new license.
Closes#2373
Fixes#1895
Changed most `println` to `info` in examples, some to `warn` when it was useful to differentiate from other more noisy logs.
Added doc on `LogPlugin`, how to configure it, and why (and how) you may need to disable it
Updates the requirements on [tracing-wasm](https://github.com/storyscript/tracing-wasm) to permit the latest version.
<details>
<summary>Commits</summary>
<ul>
<li><a href="09a0d75c45"><code>09a0d75</code></a> Disable default features for dependencies and release 0.2.0</li>
<li><a href="bbeca396ed"><code>bbeca39</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/storyscript/tracing-wasm/issues/12">#12</a> from storyscript/readme-clarification</li>
<li><a href="e35b182232"><code>e35b182</code></a> add clarifying note to README.</li>
<li><a href="259e118e7f"><code>259e118</code></a> rustfmt</li>
<li><a href="f2099cfe5e"><code>f2099cf</code></a> Apply clippy suggestions</li>
<li><a href="fde480fa11"><code>fde480f</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/storyscript/tracing-wasm/issues/6">#6</a> from storyscript/config-builder</li>
<li><a href="ad9d4b1903"><code>ad9d4b1</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/storyscript/tracing-wasm/issues/7">#7</a> from storyscript/feat/default-level</li>
<li><a href="64fedbd267"><code>64fedbd</code></a> chore(config): change level to max_level</li>
<li><a href="7cb160a7a9"><code>7cb160a</code></a> feat(level): add default level in config from the builder</li>
<li><a href="a9e7f2a4b8"><code>a9e7f2a</code></a> WIP: Builder pattern for WASMLayerConfig</li>
<li>Additional commits viewable in <a href="https://github.com/storyscript/tracing-wasm/compare/0.1.0...v0.2.0">compare view</a></li>
</ul>
</details>
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</details>
* Update tracing-chrome to 0.3.0
* bevy_log: Add fields to span names for tracing-chrome
* Conditionally import tracing_subscriber modules based on feature
