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db/Print: move sort/window emulation code to class DatabaseVisitorHelper

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That way, each plugin can decide to implement it better.
This commit is contained in:
Max Kellermann 2018-09-02 12:35:10 +02:00
parent 53170ca2f2
commit c7c32a3ce9
7 changed files with 248 additions and 92 deletions
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1
Makefile.am
View File

@ -947,6 +947,7 @@ libdb_plugins_a_SOURCES = \
src/PlaylistDatabase.cxx src/PlaylistDatabase.hxx \
src/db/Registry.cxx src/db/Registry.hxx \
src/db/Helpers.cxx src/db/Helpers.hxx \
src/db/VHelper.cxx src/db/VHelper.hxx \
src/db/UniqueTags.cxx src/db/UniqueTags.hxx \
src/db/plugins/simple/DatabaseSave.cxx \
src/db/plugins/simple/DatabaseSave.hxx \

93
src/db/DatabasePrint.cxx
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@ -144,38 +144,6 @@ PrintPlaylistFull(Response &r, bool base,
time_print(r, "Last-Modified", playlist.mtime);
}
gcc_pure
static bool
CompareNumeric(const char *a, const char *b) noexcept
{
long a_value = strtol(a, nullptr, 10);
long b_value = strtol(b, nullptr, 10);
return a_value < b_value;
}
gcc_pure
static bool
CompareTags(TagType type, bool descending, const Tag &a, const Tag &b) noexcept
{
const char *a_value = a.GetSortValue(type);
const char *b_value = b.GetSortValue(type);
if (descending) {
using std::swap;
swap(a_value, b_value);
}
switch (type) {
case TAG_DISC:
case TAG_TRACK:
return CompareNumeric(a_value, b_value);
default:
return strcmp(a_value, b_value) < 0;
}
}
void
db_selection_print(Response &r, Partition &partition,
const DatabaseSelection &selection,
@ -195,66 +163,7 @@ db_selection_print(Response &r, Partition &partition,
std::ref(r), base, _1, _2)
: VisitPlaylist();
const auto window = selection.window;
if (selection.sort == TAG_NUM_OF_ITEM_TYPES) {
unsigned i = 0;
if (!selection.window.IsAll())
s = [s, window, &i](const LightSong &song){
if (window.Contains(i++))
s(song);
};
db.Visit(selection, d, s, p);
} else {
// TODO: allow the database plugin to sort internally
/* the client has asked us to sort the result; this is
pretty expensive, because instead of streaming the
result to the client, we need to copy it all into
this std::vector, and then sort it */
std::vector<DetachedSong> songs;
{
auto collect_songs = [&songs](const LightSong &song){
songs.emplace_back(song);
};
db.Visit(selection, d, collect_songs, p);
}
const auto sort = selection.sort;
const auto descending = selection.descending;
if (sort == TagType(SORT_TAG_LAST_MODIFIED))
std::stable_sort(songs.begin(), songs.end(),
[descending](const DetachedSong &a, const DetachedSong &b){
return descending
? a.GetLastModified() > b.GetLastModified()
: a.GetLastModified() < b.GetLastModified();
});
else
std::stable_sort(songs.begin(), songs.end(),
[sort, descending](const DetachedSong &a,
const DetachedSong &b){
return CompareTags(sort, descending,
a.GetTag(),
b.GetTag());
});
if (window.end < songs.size())
songs.erase(std::next(songs.begin(), window.end),
songs.end());
if (window.start >= songs.size())
return;
songs.erase(songs.begin(),
std::next(songs.begin(), window.start));
for (const auto &song : songs)
s((LightSong)song);
}
db.Visit(selection, d, s, p);
}
static void

133
src/db/VHelper.cxx Normal file
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@ -0,0 +1,133 @@
/*
* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "VHelper.hxx"
#include "song/DetachedSong.hxx"
#include "song/LightSong.hxx"
#include "song/Filter.hxx"
#include <assert.h>
#include <string.h>
DatabaseVisitorHelper::DatabaseVisitorHelper(const DatabaseSelection &_selection,
VisitSong &visit_song) noexcept
:selection(_selection)
{
// TODO: apply URI and SongFilter
assert(selection.uri.empty());
assert(selection.filter == nullptr);
if (selection.sort != TAG_NUM_OF_ITEM_TYPES) {
/* the client has asked us to sort the result; this is
pretty expensive, because instead of streaming the
result to the client, we need to copy it all into
this std::vector, and then sort it */
original_visit_song = std::move(visit_song);
visit_song = [this](const auto &song){
songs.emplace_back(song);
};
} else if (selection.window != RangeArg::All()) {
original_visit_song = std::move(visit_song);
visit_song = [this](const auto &song){
if (selection.window.Contains(counter++))
original_visit_song(song);
};
}
}
DatabaseVisitorHelper::~DatabaseVisitorHelper() noexcept = default;
gcc_pure
static bool
CompareNumeric(const char *a, const char *b) noexcept
{
long a_value = strtol(a, nullptr, 10);
long b_value = strtol(b, nullptr, 10);
return a_value < b_value;
}
gcc_pure
static bool
CompareTags(TagType type, bool descending, const Tag &a, const Tag &b) noexcept
{
const char *a_value = a.GetSortValue(type);
const char *b_value = b.GetSortValue(type);
if (descending) {
using std::swap;
swap(a_value, b_value);
}
switch (type) {
case TAG_DISC:
case TAG_TRACK:
return CompareNumeric(a_value, b_value);
default:
return strcmp(a_value, b_value) < 0;
}
}
void
DatabaseVisitorHelper::Commit()
{
/* only needed if sorting is enabled */
if (selection.sort == TAG_NUM_OF_ITEM_TYPES)
return;
assert(original_visit_song);
/* sort the song collection */
const auto sort = selection.sort;
const auto descending = selection.descending;
if (sort == TagType(SORT_TAG_LAST_MODIFIED))
std::stable_sort(songs.begin(), songs.end(),
[descending](const DetachedSong &a, const DetachedSong &b){
return descending
? a.GetLastModified() > b.GetLastModified()
: a.GetLastModified() < b.GetLastModified();
});
else
std::stable_sort(songs.begin(), songs.end(),
[sort, descending](const DetachedSong &a,
const DetachedSong &b){
return CompareTags(sort, descending,
a.GetTag(),
b.GetTag());
});
/* apply the "window" */
if (selection.window.end < songs.size())
songs.erase(std::next(songs.begin(), selection.window.end),
songs.end());
if (selection.window.start >= songs.size())
return;
songs.erase(songs.begin(),
std::next(songs.begin(), selection.window.start));
/* now pass all songs to the original visitor callback */
for (const auto &song : songs)
original_visit_song((LightSong)song);
}

70
src/db/VHelper.hxx Normal file
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@ -0,0 +1,70 @@
/*
* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_DATABASE_VISITOR_HELPER_HXX
#define MPD_DATABASE_VISITOR_HELPER_HXX
#include "Visitor.hxx"
#include "Selection.hxx"
#include <vector>
class DetachedSong;
/**
* This class helps implementing Database::Visit() by emulating
* #DatabaseSelection features that the #Database implementation
* doesn't have, e.g. filtering, sorting and window.
*
* To use this class, construct it, passing unsupported features and
* the visitor callback to the constructor; before leaving Visit(),
* call Commit() (unless an error has occurred).
*/
class DatabaseVisitorHelper {
const DatabaseSelection selection;
/**
* If the plugin can't sort, then this container will collect
* all songs, sort them and report them to the visitor in
* Commit().
*/
std::vector<DetachedSong> songs;
VisitSong original_visit_song;
/**
* Used to emulate the "window".
*/
unsigned counter = 0;
public:
/**
* @param selection a #DatabaseSelection instance with only
* features enabled which shall be emulated by this class
* @param visit_song the callback function passed to
* Database::Visit(); may be replaced by this class
*/
DatabaseVisitorHelper(const DatabaseSelection &selection,
VisitSong &visit_song) noexcept;
~DatabaseVisitorHelper() noexcept;
void Commit();
};
#endif

15
src/db/plugins/ProxyDatabasePlugin.cxx
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@ -23,6 +23,7 @@
#include "db/DatabasePlugin.hxx"
#include "db/DatabaseListener.hxx"
#include "db/Selection.hxx"
#include "db/VHelper.hxx"
#include "db/DatabaseError.hxx"
#include "db/PlaylistInfo.hxx"
#include "db/LightDirectory.hxx"
@ -804,6 +805,15 @@ try {
throw;
}
gcc_const
static DatabaseSelection
CheckSelection(DatabaseSelection selection) noexcept
{
selection.uri.clear();
selection.filter = nullptr;
return selection;
}
void
ProxyDatabase::Visit(const DatabaseSelection &selection,
VisitDirectory visit_directory,
@ -813,11 +823,14 @@ ProxyDatabase::Visit(const DatabaseSelection &selection,
// TODO: eliminate the const_cast
const_cast<ProxyDatabase *>(this)->EnsureConnected();
DatabaseVisitorHelper helper(CheckSelection(selection), visit_song);
if (!visit_directory && !visit_playlist && selection.recursive &&
!selection.IsEmpty()) {
/* this optimized code path can only be used under
certain conditions */
::SearchSongs(connection, selection, visit_song);
helper.Commit();
return;
}
@ -825,6 +838,8 @@ ProxyDatabase::Visit(const DatabaseSelection &selection,
::Visit(connection, selection.uri.c_str(),
selection.recursive, selection.filter,
visit_directory, visit_song, visit_playlist);
helper.Commit();
}
void

14
src/db/plugins/simple/SimpleDatabasePlugin.cxx
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@ -26,6 +26,7 @@
#include "db/Helpers.hxx"
#include "db/Stats.hxx"
#include "db/UniqueTags.hxx"
#include "db/VHelper.hxx"
#include "db/LightDirectory.hxx"
#include "Directory.hxx"
#include "Song.hxx"
@ -265,6 +266,15 @@ SimpleDatabase::ReturnSong(gcc_unused const LightSong *song) const noexcept
}
}
gcc_const
static DatabaseSelection
CheckSelection(DatabaseSelection selection) noexcept
{
selection.uri.clear();
selection.filter = nullptr;
return selection;
}
void
SimpleDatabase::Visit(const DatabaseSelection &selection,
VisitDirectory visit_directory,
@ -286,6 +296,8 @@ SimpleDatabase::Visit(const DatabaseSelection &selection,
return;
}
DatabaseVisitorHelper helper(CheckSelection(selection), visit_song);
if (r.uri == nullptr) {
/* it's a directory */
@ -295,6 +307,7 @@ SimpleDatabase::Visit(const DatabaseSelection &selection,
r.directory->Walk(selection.recursive, selection.filter,
visit_directory, visit_song,
visit_playlist);
helper.Commit();
return;
}
@ -306,6 +319,7 @@ SimpleDatabase::Visit(const DatabaseSelection &selection,
if (selection.Match(song2))
visit_song(song2);
helper.Commit();
return;
}
}

14
src/db/plugins/upnp/UpnpDatabasePlugin.cxx
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@ -27,6 +27,7 @@
#include "db/Interface.hxx"
#include "db/DatabasePlugin.hxx"
#include "db/Selection.hxx"
#include "db/VHelper.hxx"
#include "db/DatabaseError.hxx"
#include "db/LightDirectory.hxx"
#include "song/LightSong.hxx"
@ -576,6 +577,15 @@ UpnpDatabase::VisitServer(const ContentDirectoryService &server,
}
}
gcc_const
static DatabaseSelection
CheckSelection(DatabaseSelection selection) noexcept
{
selection.uri.clear();
selection.filter = nullptr;
return selection;
}
// Deal with the possibly multiple servers, call VisitServer if needed.
void
UpnpDatabase::Visit(const DatabaseSelection &selection,
@ -583,6 +593,8 @@ UpnpDatabase::Visit(const DatabaseSelection &selection,
VisitSong visit_song,
VisitPlaylist visit_playlist) const
{
DatabaseVisitorHelper helper(CheckSelection(selection), visit_song);
auto vpath = SplitString(selection.uri.c_str(), '/');
if (vpath.empty()) {
for (const auto &server : discovery->GetDirectories()) {
@ -598,6 +610,7 @@ UpnpDatabase::Visit(const DatabaseSelection &selection,
visit_playlist);
}
helper.Commit();
return;
}
@ -608,6 +621,7 @@ UpnpDatabase::Visit(const DatabaseSelection &selection,
auto server = discovery->GetServer(servername.c_str());
VisitServer(server, std::move(vpath), selection,
visit_directory, visit_song, visit_playlist);
helper.Commit();
}
void