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depot_query: remove ineffective caches
Upon closer inspection of real-world access patterns, it turns out that the 'Stat_cache' and 'Cached_rom_query' are not as effective as hoped for because cache hits are rare while querying pkg blueprints. However, by increasing the initial size of the blueprint reporter from 4 KiB (default) to 64 KiB has a great effect. With the small default report size, the querying of blueprints is repeated until the buffer size suffices, incrementing the buffer size by 4 KiB in each iteration. Issue #4611
This commit is contained in:
Norman Feske
parent
3be0136901
commit
b4441bff04
@ -18,7 +18,6 @@
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#include <os/reporter.h>
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#include <os/vfs.h>
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#include <depot/archive.h>
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#include <gems/lru_cache.h>
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/* fs_query includes */
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#include <for_each_subdir_name.h>
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@ -31,9 +30,6 @@ namespace Depot_query {
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struct Recursion_limit;
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struct Dependencies;
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class Stat_cache;
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struct Rom_query;
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class Cached_rom_query;
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struct Main;
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}
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@ -155,172 +151,7 @@ class Depot_query::Dependencies
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};
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class Depot_query::Stat_cache
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{
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private:
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struct Key
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{
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struct Value
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{
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Archive::Path path;
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bool operator > (Value const &other) const
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{
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return strcmp(path.string(), other.path.string()) > 0;
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}
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bool operator == (Value const &other) const
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{
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return path == other.path;
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}
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} value;
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};
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struct Result { bool file_exists; };
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typedef Lru_cache<Key, Result> Cache;
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Cache::Size const _size;
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Cache _cache;
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Directory const &_dir;
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public:
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Stat_cache(Directory const &dir, Allocator &alloc, Xml_node const config)
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:
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_size({.value = config.attribute_value("stat_cache", Number_of_bytes(64*1024))
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/ Cache::element_size()}),
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_cache(alloc, _size),
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_dir(dir)
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{ }
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bool file_exists(Archive::Path const path)
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{
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/* don't cache the state of the 'local' depot user */
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if (Archive::user(path) == "local")
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return _dir.file_exists(path);
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bool result = false;
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auto hit_fn = [&] (Result const &cached_result)
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{
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result = cached_result.file_exists;
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};
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auto miss_fn = [&] (Cache::Missing_element &missing_element)
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{
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Result const stat_result { _dir.file_exists(path) };
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/*
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* Don't cache negative results because files may appear
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* during installation. Later queries may find files absent
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* from earlier queries.
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*/
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if (stat_result.file_exists)
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missing_element.construct(stat_result);
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};
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Key const key { .value = { .path = path } };
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(void)_cache.try_apply(key, hit_fn, miss_fn);
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return result;
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}
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};
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struct Depot_query::Rom_query : Interface
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{
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/**
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* Look up ROM module 'rom_label' in the archives referenced by 'pkg_path'
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*
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* \throw Directory::Nonexistent_directory
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* \throw Directory::Nonexistent_file
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* \throw File::Truncated_during_read
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* \throw Recursion_limit::Reached
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*/
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virtual Archive::Path find_rom_in_pkg(Directory::Path const &pkg_path,
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Rom_label const &rom_label,
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Recursion_limit recursion_limit) = 0;
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};
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class Depot_query::Cached_rom_query : public Rom_query
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{
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private:
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struct Key
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{
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struct Value
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{
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Archive::Path pkg;
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Rom_label rom;
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bool operator > (Value const &other) const
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{
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return strcmp(pkg.string(), other.pkg.string()) > 0
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&& strcmp(rom.string(), other.rom.string()) > 0;
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}
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bool operator == (Value const &other) const
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{
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return pkg == other.pkg && rom == other.rom;
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}
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} value;
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};
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typedef Lru_cache<Key, Archive::Path> Cache;
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Cache::Size const _size;
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Cache mutable _cache;
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Rom_query &_rom_query;
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public:
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Cached_rom_query(Rom_query &rom_query, Allocator &alloc, Xml_node const config)
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:
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_size({.value = config.attribute_value("rom_query_cache", Number_of_bytes(64*1024))
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/ Cache::element_size() }),
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_cache(alloc, _size),
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_rom_query(rom_query)
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{ }
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Archive::Path find_rom_in_pkg(Directory::Path const &pkg_path,
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Rom_label const &rom_label,
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Recursion_limit recursion_limit) override
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{
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/* don't cache the state of the 'local' depot user */
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if (Archive::user(pkg_path) == "local")
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return _rom_query.find_rom_in_pkg(pkg_path, rom_label, recursion_limit);
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Archive::Path result { };
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auto hit_fn = [&] (Archive::Path const &path) { result = path; };
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auto miss_fn = [&] (Cache::Missing_element &missing_element)
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{
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Archive::Path const path =
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_rom_query.find_rom_in_pkg(pkg_path, rom_label, recursion_limit);
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if (path.valid())
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missing_element.construct(path);
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};
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Key const key { .value = { .pkg = pkg_path, .rom = rom_label } };
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(void)_cache.try_apply(key, hit_fn, miss_fn);
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return result;
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}
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};
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struct Depot_query::Main : private Rom_query
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struct Depot_query::Main
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{
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Env &_env;
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@ -334,8 +165,6 @@ struct Depot_query::Main : private Rom_query
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Directory _depot_dir { _root, "depot" };
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Stat_cache _depot_stat_cache { _depot_dir, _heap, _config.xml() };
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Signal_handler<Main> _config_handler {
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_env.ep(), *this, &Main::_handle_config };
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@ -365,6 +194,11 @@ struct Depot_query::Main : private Rom_query
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Architecture _architecture { };
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bool _file_exists(Directory::Path const &path)
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{
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return _depot_dir.file_exists(path);
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}
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template <typename FN>
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void _with_file_content(Directory::Path const &path, char const *name, FN const &fn)
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{
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@ -399,13 +233,7 @@ struct Depot_query::Main : private Rom_query
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});
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}
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Cached_rom_query _cached_rom_query { *this, _heap, _config.xml() };
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/**
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* Rom_query interface
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*/
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Archive::Path find_rom_in_pkg(Directory::Path const &, Rom_label const &,
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Recursion_limit) override;
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Archive::Path _find_rom_in_pkg(Directory::Path const &, Rom_label const &, Recursion_limit);
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void _gen_rom_path_nodes(Xml_generator &, Xml_node const &,
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Archive::Path const &, Xml_node const &);
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@ -449,8 +277,13 @@ struct Depot_query::Main : private Rom_query
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_construct_if(query.has_sub_node("scan"),
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_scan_reporter, _env, "scan", "scan");
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/*
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* Use 64 KiB as initial report size to avoid the repetitive querying
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* when successively expanding the reporter.
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*/
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_construct_if(query.has_sub_node("blueprint"),
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_blueprint_reporter, _env, "blueprint", "blueprint");
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_blueprint_reporter, _env, "blueprint", "blueprint",
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Expanding_reporter::Initial_buffer_size { 64*1024 });
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_construct_if(query.has_sub_node("dependencies"),
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_dependencies_reporter, _env, "dependencies", "dependencies");
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@ -535,9 +368,9 @@ struct Depot_query::Main : private Rom_query
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Depot_query::Archive::Path
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Depot_query::Main::find_rom_in_pkg(Directory::Path const &pkg_path,
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Rom_label const &rom_label,
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Recursion_limit recursion_limit)
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Depot_query::Main::_find_rom_in_pkg(Directory::Path const &pkg_path,
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Rom_label const &rom_label,
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Recursion_limit recursion_limit)
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{
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/*
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* \throw Directory::Nonexistent_directory
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@ -566,7 +399,7 @@ Depot_query::Main::find_rom_in_pkg(Directory::Path const &pkg_path,
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Archive::name(archive_path), "/",
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Archive::version(archive_path), "/", rom_label);
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if (_depot_stat_cache.file_exists(rom_path))
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if (_file_exists(rom_path))
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result = rom_path;
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}
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break;
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@ -578,7 +411,7 @@ Depot_query::Main::find_rom_in_pkg(Directory::Path const &pkg_path,
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Archive::name(archive_path), "/",
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Archive::version(archive_path), "/", rom_label);
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if (_depot_stat_cache.file_exists(rom_path))
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if (_file_exists(rom_path))
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result = rom_path;
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}
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break;
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@ -586,7 +419,7 @@ Depot_query::Main::find_rom_in_pkg(Directory::Path const &pkg_path,
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case Archive::PKG:
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Archive::Path const result_from_pkg =
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_cached_rom_query.find_rom_in_pkg(archive_path, rom_label, recursion_limit);
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_find_rom_in_pkg(archive_path, rom_label, recursion_limit);
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if (result_from_pkg.valid())
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result = result_from_pkg;
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@ -627,7 +460,7 @@ void Depot_query::Main::_gen_rom_path_nodes(Xml_generator &xml,
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}
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Archive::Path const rom_path =
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_cached_rom_query.find_rom_in_pkg(pkg_path, label, Recursion_limit{8});
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_find_rom_in_pkg(pkg_path, label, Recursion_limit{8});
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if (rom_path.valid()) {
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xml.node("rom", [&] () {
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