155 lines
9.8 KiB
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155 lines
9.8 KiB
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<!DOCTYPE html>
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<html>
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<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>Garbage Collection Functions (Guile Reference Manual)</title>
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<meta name="description" content="Garbage Collection Functions (Guile Reference Manual)">
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<meta name="keywords" content="Garbage Collection Functions (Guile Reference Manual)">
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<link href="index.html" rel="start" title="Top">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Memory-Management.html" rel="up" title="Memory Management">
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<link href="Memory-Blocks.html" rel="next" title="Memory Blocks">
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</head>
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<body lang="en">
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<div class="subsection-level-extent" id="Garbage-Collection-Functions">
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<div class="nav-panel">
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<p>
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Next: <a href="Memory-Blocks.html" accesskey="n" rel="next">Memory Blocks</a>, Up: <a href="Memory-Management.html" accesskey="u" rel="up">Memory Management and Garbage Collection</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<h4 class="subsection" id="Function-related-to-Garbage-Collection"><span>6.17.1 Function related to Garbage Collection<a class="copiable-link" href="#Function-related-to-Garbage-Collection"> ¶</a></span></h4>
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<dl class="first-deffn">
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<dt class="deffn" id="index-gc-1"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">gc</strong><a class="copiable-link" href="#index-gc-1"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fgc"><span class="category-def">C Function: </span><span><strong class="def-name">scm_gc</strong> <var class="def-var-arguments">()</var><a class="copiable-link" href="#index-scm_005fgc"> ¶</a></span></dt>
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<dd><p>Finds all of the “live” <code class="code">SCM</code> objects and reclaims for further
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use those that are no longer accessible. You normally don’t need to
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call this function explicitly. Its functionality is invoked
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automatically as needed.
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</p></dd></dl>
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<dl class="first-deftypefn">
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<dt class="deftypefn" id="index-scm_005fgc_005fprotect_005fobject"><span class="category-def">C Function: </span><span><code class="def-type">SCM</code> <strong class="def-name">scm_gc_protect_object</strong> <code class="def-code-arguments">(SCM <var class="var">obj</var>)</code><a class="copiable-link" href="#index-scm_005fgc_005fprotect_005fobject"> ¶</a></span></dt>
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<dd><p>Protects <var class="var">obj</var> from being freed by the garbage collector, when it
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otherwise might be. When you are done with the object, call
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<code class="code">scm_gc_unprotect_object</code> on the object. Calls to
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<code class="code">scm_gc_protect_object</code>/<code class="code">scm_gc_unprotect_object</code> can be nested, and
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the object remains protected until it has been unprotected as many times
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as it was protected. It is an error to unprotect an object more times
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than it has been protected. Returns the SCM object it was passed.
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</p>
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<p>Note that storing <var class="var">obj</var> in a C global variable has the same
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effect<a class="footnote" id="DOCF17" href="#FOOT17"><sup>17</sup></a>.
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</p></dd></dl>
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<dl class="first-deftypefn">
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<dt class="deftypefn" id="index-scm_005fgc_005funprotect_005fobject"><span class="category-def">C Function: </span><span><code class="def-type">SCM</code> <strong class="def-name">scm_gc_unprotect_object</strong> <code class="def-code-arguments">(SCM <var class="var">obj</var>)</code><a class="copiable-link" href="#index-scm_005fgc_005funprotect_005fobject"> ¶</a></span></dt>
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<dd>
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<p>Unprotects an object from the garbage collector which was protected by
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<code class="code">scm_gc_unprotect_object</code>. Returns the SCM object it was passed.
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</p></dd></dl>
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<dl class="first-deftypefn">
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<dt class="deftypefn" id="index-scm_005fpermanent_005fobject"><span class="category-def">C Function: </span><span><code class="def-type">SCM</code> <strong class="def-name">scm_permanent_object</strong> <code class="def-code-arguments">(SCM <var class="var">obj</var>)</code><a class="copiable-link" href="#index-scm_005fpermanent_005fobject"> ¶</a></span></dt>
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<dd>
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<p>Similar to <code class="code">scm_gc_protect_object</code> in that it causes the
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collector to always mark the object, except that it should not be
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nested (only call <code class="code">scm_permanent_object</code> on an object once), and
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it has no corresponding unpermanent function. Once an object is
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declared permanent, it will never be freed. Returns the SCM object it
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was passed.
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</p></dd></dl>
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<dl class="first-deftypefn">
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<dt class="deftypefn" id="index-scm_005fremember_005fupto_005fhere_005f1"><span class="category-def">C Macro: </span><span><code class="def-type">void</code> <strong class="def-name">scm_remember_upto_here_1</strong> <code class="def-code-arguments">(SCM obj)</code><a class="copiable-link" href="#index-scm_005fremember_005fupto_005fhere_005f1"> ¶</a></span></dt>
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<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fremember_005fupto_005fhere_005f2"><span class="category-def">C Macro: </span><span><code class="def-type">void</code> <strong class="def-name">scm_remember_upto_here_2</strong> <code class="def-code-arguments">(SCM obj1, SCM obj2)</code><a class="copiable-link" href="#index-scm_005fremember_005fupto_005fhere_005f2"> ¶</a></span></dt>
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<dd><p>Create a reference to the given object or objects, so they’re certain
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to be present on the stack or in a register and hence will not be
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freed by the garbage collector before this point.
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</p>
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<p>Note that these functions can only be applied to ordinary C local
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variables (ie. “automatics”). Objects held in global or static
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variables or some malloced block or the like cannot be protected with
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this mechanism.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-gc_002dstats"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">gc-stats</strong><a class="copiable-link" href="#index-gc_002dstats"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fgc_005fstats"><span class="category-def">C Function: </span><span><strong class="def-name">scm_gc_stats</strong> <var class="def-var-arguments">()</var><a class="copiable-link" href="#index-scm_005fgc_005fstats"> ¶</a></span></dt>
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<dd><p>Return an association list of statistics about Guile’s current
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use of storage.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-gc_002dlive_002dobject_002dstats"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">gc-live-object-stats</strong><a class="copiable-link" href="#index-gc_002dlive_002dobject_002dstats"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fgc_005flive_005fobject_005fstats"><span class="category-def">C Function: </span><span><strong class="def-name">scm_gc_live_object_stats</strong> <var class="def-var-arguments">()</var><a class="copiable-link" href="#index-scm_005fgc_005flive_005fobject_005fstats"> ¶</a></span></dt>
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<dd><p>Return an alist of statistics of the current live objects.
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</p></dd></dl>
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<dl class="first-deftypefn first-deftypefun-alias-first-deftypefn">
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<dt class="deftypefn deftypefun-alias-deftypefn" id="index-scm_005fgc_005fmark"><span class="category-def">Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_gc_mark</strong> <code class="def-code-arguments">(SCM <var class="var">x</var>)</code><a class="copiable-link" href="#index-scm_005fgc_005fmark"> ¶</a></span></dt>
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<dd><p>Mark the object <var class="var">x</var>, and recurse on any objects <var class="var">x</var> refers to.
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If <var class="var">x</var>’s mark bit is already set, return immediately. This function
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must only be called during the mark-phase of garbage collection,
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typically from a smob <em class="emph">mark</em> function.
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</p></dd></dl>
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</div>
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<div class="footnotes-segment">
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<hr>
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<h4 class="footnotes-heading">Footnotes</h4>
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<h5 class="footnote-body-heading"><a id="FOOT17" href="#DOCF17">(17)</a></h5>
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<p>In Guile up to version 1.8, C global variables were not
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visited by the garbage collector in the mark phase; hence,
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<code class="code">scm_gc_protect_object</code> was the only way in C to prevent a Scheme
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object from being freed.</p>
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</div>
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<hr>
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<div class="nav-panel">
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<p>
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Next: <a href="Memory-Blocks.html">Memory Blocks</a>, Up: <a href="Memory-Management.html">Memory Management and Garbage Collection</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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