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22 lines
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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Run the body of a JNI callback with any panic contained."><title>jni_guard in jellytau_lib::player::jni_guard - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../../static.files/rustdoc-17e0aaed.css"><meta name="rustdoc-vars" data-root-path="../../../" data-static-root-path="../../../static.files/" data-current-crate="jellytau_lib" data-themes="" data-resource-suffix="" data-rustdoc-version="1.97.1 (8bab26f4f 2026-07-14)" data-channel="1.97.1" data-search-js="search-fd9372ac.js" data-stringdex-js="stringdex-2da4960a.js" data-settings-js="settings-170eb4bf.js" ><script src="../../../static.files/storage-41dd4d93.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../../static.files/main-fcd733ba.js"></script><noscript><link rel="stylesheet" href="../../../static.files/noscript-f7c3ffd8.css"></noscript><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../../static.files/favicon-044be391.svg"></head><body class="rustdoc fn"><a class="skip-main-content" href="#main-content">Skip to main content</a><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><rustdoc-topbar><h2><a href="#">jni_guard</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../../jellytau_lib/index.html">jellytau_<wbr>lib</a><span class="version">0.11.6</span></h2></div><div class="sidebar-elems"><div id="rustdoc-modnav"><h2><a href="index.html">In jellytau_<wbr>lib::<wbr>player::<wbr>jni_<wbr>guard</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content" tabindex="-1"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../../index.html">jellytau_lib</a>::<wbr><a href="../index.html">player</a>::<wbr><a href="index.html">jni_guard</a></div><h1>Function <span class="fn">jni_<wbr>guard</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../../../src/jellytau_lib/player/jni_guard.rs.html#34-42">Source</a> </span></div><pre class="rust item-decl"><code>pub(crate) fn jni_guard<F: <a class="trait" href="https://doc.rust-lang.org/1.97.1/core/ops/function/trait.FnOnce.html" title="trait core::ops::function::FnOnce">FnOnce</a>()>(name: &<a class="primitive" href="https://doc.rust-lang.org/1.97.1/std/primitive.str.html">str</a>, body: F)</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Run the body of a JNI callback with any panic contained.</p>
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<p>Every <code>extern "system"</code> function in this file is called by the JVM on an
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arbitrary thread. A panic that unwinds out of one crosses the FFI boundary,
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which Rust answers by <strong>aborting the process</strong> — the app vanishes with no
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Java exception, no stack trace attributable to it, and no crash report the
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user can send. That is the worst possible failure mode for the callbacks
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that fire four times a second during playback.</p>
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<p>The panics are real, not theoretical: this file builds a fallback Tokio
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runtime on threads that have none, and <code>Runtime::new()</code> fails under the fd
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exhaustion and thread-spawn refusal an Android device puts a media app
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through. Losing one position report is recoverable; losing the process is
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not.</p>
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<p>A contained panic still leaves whatever it interrupted half-done, so this is
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a backstop, not a licence to panic. <code>utils::lock</code> already keeps a poisoned
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mutex from cascading; this keeps the FFI boundary from turning any remaining
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panic into a process kill.</p>
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<p>TRACES: UR-005 | DR-052</p>
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<p>Only <em>called</em> from <code>player::android</code>, which is <code>cfg(target_os = "android")</code>,
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so it is dead code on every other target — the same reason
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<code>RESUME_BACKOFF_STEP_SECS</code> carries this attribute. It is still compiled and
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tested here on purpose.</p>
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</div></details></section></div></main></body></html> |