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/* Caching of GDB/DWARF index files.
Copyright (C) 2018-2024 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef DWARF_INDEX_CACHE_H
#define DWARF_INDEX_CACHE_H
#include "gdbsupport/array-view.h"
class dwarf2_per_bfd;
class index_cache;
/* Base of the classes used to hold the resources of the indices loaded from
the cache (e.g. mmapped files). */
struct index_cache_resource
{
virtual ~index_cache_resource () = 0;
};
/* Information to be captured in the main thread, and to be used by worker
threads during store (). */
struct index_cache_store_context
{
index_cache_store_context (const index_cache &ic, dwarf2_per_bfd *per_bfd);
/* Store the index in the cache. */
void store () const;
private:
/* Captured value of enabled (). */
bool m_enabled;
/* Captured value of index cache directory. */
std::string m_dir;
/* The per-bfd object that we're caching. */
dwarf2_per_bfd *m_per_bfd;
/* Captured value of build id. */
std::string m_build_id_str;
/* Captured value of dwz build id. */
std::optional<std::string> m_dwz_build_id_str;
};
/* Class to manage the access to the DWARF index cache. */
class index_cache
{
friend struct index_cache_store_context;
public:
/* Change the directory used to save/load index files. */
void set_directory (std::string dir);
/* Return true if the usage of the cache is enabled. */
bool enabled () const
{
return m_enabled;
}
/* Enable the cache. */
void enable ();
/* Disable the cache. */
void disable ();
/* Look for an index file matching BUILD_ID. If found, return the contents
as an array_view and store the underlying resources (allocated memory,
mapped file, etc) in RESOURCE. The returned array_view is valid as long
as RESOURCE is not destroyed.
If no matching index file is found, return an empty array view. */
gdb::array_view<const gdb_byte>
lookup_gdb_index (const bfd_build_id *build_id,
std::unique_ptr<index_cache_resource> *resource);
/* Return the number of cache hits. */
unsigned int n_hits () const
{ return m_n_hits; }
/* Record a cache hit. */
void hit ()
{
if (enabled ())
m_n_hits++;
}
/* Return the number of cache misses. */
unsigned int n_misses () const
{ return m_n_misses; }
/* Record a cache miss. */
void miss ()
{
if (enabled ())
m_n_misses++;
}
private:
/* Compute the absolute filename where the index of the objfile with build
id BUILD_ID will be stored. SUFFIX is appended at the end of the
filename. */
std::string make_index_filename (const bfd_build_id *build_id,
const char *suffix) const;
/* The base directory where we are storing and looking up index files. */
std::string m_dir;
/* Whether the cache is enabled. */
bool m_enabled = false;
/* Number of cache hits and misses during this GDB session. */
unsigned int m_n_hits = 0;
unsigned int m_n_misses = 0;
};
/* The global instance of the index cache. */
extern index_cache global_index_cache;
#endif /* DWARF_INDEX_CACHE_H */
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