forked from Imagelibrary/binutils-gdb
bf803c840c
At the beginning of a session, gdb may attempt to download debuginfo for all shared libraries associated with the process or core file being debugged. This can be a waste of time and storage space when much of the debuginfo ends up not being used during the session. To reduce the gdb's startup latency and to download only the debuginfo that is really needed, this patch adds on-demand, a.k.a lazy, downloading. When 'set debuginfo enabled lazy' is on, gdb will attempt to download a .gdb_index for each shared library instead of its full debuginfo. Each debuginfo download will be deferred until gdb needs to expand symtabs associated with the debuginfo's index. Additionally, all separate debug objfiles are placed in objfiles_list after their parent, instead of before. This ensures that any deferred debuginfo downloaded during iteration over objfiles_list aren't skipped by the loop. I also modified objfiles_safe so that it returns a safe reverse iterator. Reverse iteration prevents iterator invalidation by ensuring that separate debug objfiles are deleted before their parent objfile.
128 lines
3.7 KiB
C++
128 lines
3.7 KiB
C++
/* Caching of GDB/DWARF index files.
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Copyright (C) 2018-2023 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef DWARF_INDEX_CACHE_H
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#define DWARF_INDEX_CACHE_H
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#include "dwarf2/index-common.h"
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#include "gdbsupport/array-view.h"
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#include "symfile.h"
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class dwarf2_per_bfd;
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/* Base of the classes used to hold the resources of the indices loaded from
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the cache (e.g. mmapped files). */
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struct index_cache_resource
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{
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virtual ~index_cache_resource () = 0;
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};
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/* Class to manage the access to the DWARF index cache. */
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class index_cache
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{
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public:
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/* Change the directory used to save/load index files. */
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void set_directory (std::string dir);
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/* Return true if the usage of the cache is enabled. */
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bool enabled () const
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{
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return m_enabled;
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}
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/* Enable the cache. */
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void enable ();
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/* Disable the cache. */
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void disable ();
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/* Store an index for the specified object file in the cache. */
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void store (dwarf2_per_bfd *per_bfd);
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/* Look for an index file matching BUILD_ID. If found, return the contents
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as an array_view and store the underlying resources (allocated memory,
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mapped file, etc) in RESOURCE. The returned array_view is valid as long
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as RESOURCE is not destroyed.
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If no matching index file is found, return an empty array view. */
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gdb::array_view<const gdb_byte>
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lookup_gdb_index (const bfd_build_id *build_id,
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std::unique_ptr<index_cache_resource> *resource);
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/* Look for an index file located at INDEX_PATH in the debuginfod cache.
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Unlike lookup_gdb_index, this function does not exit early if the
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index cache has not been enabled.
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If found, return the contents as an array_view and store the underlying
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resources (allocated memory, mapped file, etc) in RESOURCE. The returned
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array_view is valid as long as RESOURCE is not destroyed.
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If no matching index file is found, return an empty array view. */
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gdb::array_view<const gdb_byte>
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lookup_gdb_index_debuginfod (const char *index_path,
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std::unique_ptr<index_cache_resource> *resource);
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/* Return the number of cache hits. */
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unsigned int n_hits () const
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{ return m_n_hits; }
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/* Record a cache hit. */
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void hit ()
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{
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if (enabled ())
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m_n_hits++;
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}
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/* Return the number of cache misses. */
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unsigned int n_misses () const
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{ return m_n_misses; }
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/* Record a cache miss. */
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void miss ()
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{
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if (enabled ())
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m_n_misses++;
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}
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private:
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/* Compute the absolute filename where the index of the objfile with build
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id BUILD_ID will be stored. SUFFIX is appended at the end of the
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filename. */
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std::string make_index_filename (const bfd_build_id *build_id,
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const char *suffix) const;
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/* The base directory where we are storing and looking up index files. */
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std::string m_dir;
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/* Whether the cache is enabled. */
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bool m_enabled = false;
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/* Number of cache hits and misses during this GDB session. */
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unsigned int m_n_hits = 0;
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unsigned int m_n_misses = 0;
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};
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/* The global instance of the index cache. */
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extern index_cache global_index_cache;
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#endif /* DWARF_INDEX_CACHE_H */
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