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Systemd/src/core/manager.h
Lennart Poettering a57f7e2c82 core: rework how we match mount units against each other 
Previously to automatically create dependencies between mount units we
matched every mount unit agains all others resulting in O(n^2)
complexity. On setups with large amounts of mount units this might make
things slow.

This change replaces the matching code to use a hashtable that is keyed
by a path prefix, and points to a set of units that require that path to
be around. When a new mount unit is installed it is hence sufficient to
simply look up this set of units via its own file system paths to know
which units to order after itself.

This patch also changes all unit types to only create automatic mount
dependencies via the RequiresMountsFor= logic, and this is exposed to
the outside to make things more transparent.

With this change we still have some O(n) complexities in place when
handling mounts, but that's currently unavoidable due to kernel APIs,
and still substantially better than O(n^2) as before.

https://bugs.freedesktop.org/show_bug.cgi?id=69740
2013-09-26 20:20:30 +02:00

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
#pragma once
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdbool.h>
#include <inttypes.h>
#include <stdio.h>
#include <dbus/dbus.h>
#include "fdset.h"
#include "cgroup-util.h"
/* Enforce upper limit how many names we allow */
#define MANAGER_MAX_NAMES 131072 /* 128K */
typedef struct Manager Manager;
typedef enum WatchType WatchType;
typedef struct Watch Watch;
typedef enum ManagerExitCode {
MANAGER_RUNNING,
MANAGER_EXIT,
MANAGER_RELOAD,
MANAGER_REEXECUTE,
MANAGER_REBOOT,
MANAGER_POWEROFF,
MANAGER_HALT,
MANAGER_KEXEC,
MANAGER_SWITCH_ROOT,
_MANAGER_EXIT_CODE_MAX,
_MANAGER_EXIT_CODE_INVALID = -1
} ManagerExitCode;
enum WatchType {
WATCH_INVALID,
WATCH_SIGNAL,
WATCH_NOTIFY,
WATCH_FD,
WATCH_UNIT_TIMER,
WATCH_JOB_TIMER,
WATCH_MOUNT,
WATCH_SWAP,
WATCH_UDEV,
WATCH_DBUS_WATCH,
WATCH_DBUS_TIMEOUT,
WATCH_TIME_CHANGE,
WATCH_JOBS_IN_PROGRESS,
WATCH_IDLE_PIPE,
};
struct Watch {
int fd;
WatchType type;
union {
struct Unit *unit;
struct Job *job;
DBusWatch *bus_watch;
DBusTimeout *bus_timeout;
} data;
bool fd_is_dupped:1;
bool socket_accept:1;
};
#include "unit.h"
#include "job.h"
#include "hashmap.h"
#include "list.h"
#include "set.h"
#include "dbus.h"
#include "path-lookup.h"
#include "execute.h"
#include "unit-name.h"
struct Manager {
/* Note that the set of units we know of is allowed to be
* inconsistent. However the subset of it that is loaded may
* not, and the list of jobs may neither. */
/* Active jobs and units */
Hashmap *units; /* name string => Unit object n:1 */
Hashmap *jobs; /* job id => Job object 1:1 */
/* To make it easy to iterate through the units of a specific
* type we maintain a per type linked list */
LIST_HEAD(Unit, units_by_type[_UNIT_TYPE_MAX]);
/* Units that need to be loaded */
LIST_HEAD(Unit, load_queue); /* this is actually more a stack than a queue, but uh. */
/* Jobs that need to be run */
LIST_HEAD(Job, run_queue); /* more a stack than a queue, too */
/* Units and jobs that have not yet been announced via
* D-Bus. When something about a job changes it is added here
* if it is not in there yet. This allows easy coalescing of
* D-Bus change signals. */
LIST_HEAD(Unit, dbus_unit_queue);
LIST_HEAD(Job, dbus_job_queue);
/* Units to remove */
LIST_HEAD(Unit, cleanup_queue);
/* Units to check when doing GC */
LIST_HEAD(Unit, gc_queue);
/* Units that should be realized */
LIST_HEAD(Unit, cgroup_queue);
Hashmap *watch_pids; /* pid => Unit object n:1 */
char *notify_socket;
Watch notify_watch;
Watch signal_watch;
Watch time_change_watch;
Watch jobs_in_progress_watch;
Watch idle_pipe_watch;
int epoll_fd;
unsigned n_snapshots;
LookupPaths lookup_paths;
Set *unit_path_cache;
char **environment;
usec_t runtime_watchdog;
usec_t shutdown_watchdog;
dual_timestamp firmware_timestamp;
dual_timestamp loader_timestamp;
dual_timestamp kernel_timestamp;
dual_timestamp initrd_timestamp;
dual_timestamp userspace_timestamp;
dual_timestamp finish_timestamp;
dual_timestamp generators_start_timestamp;
dual_timestamp generators_finish_timestamp;
dual_timestamp unitsload_start_timestamp;
dual_timestamp unitsload_finish_timestamp;
char *generator_unit_path;
char *generator_unit_path_early;
char *generator_unit_path_late;
/* Data specific to the device subsystem */
struct udev* udev;
struct udev_monitor* udev_monitor;
Watch udev_watch;
Hashmap *devices_by_sysfs;
/* Data specific to the mount subsystem */
FILE *proc_self_mountinfo;
Watch mount_watch;
/* Data specific to the swap filesystem */
FILE *proc_swaps;
Hashmap *swaps_by_proc_swaps;
bool request_reload;
Watch swap_watch;
/* Data specific to the D-Bus subsystem */
DBusConnection *api_bus, *system_bus;
DBusServer *private_bus;
Set *bus_connections, *bus_connections_for_dispatch;
DBusMessage *queued_message; /* This is used during reloading:
* before the reload we queue the
* reply message here, and
* afterwards we send it */
DBusConnection *queued_message_connection; /* The connection to send the queued message on */
Hashmap *watch_bus; /* D-Bus names => Unit object n:1 */
int32_t name_data_slot;
int32_t conn_data_slot;
int32_t subscribed_data_slot;
bool send_reloading_done;
uint32_t current_job_id;
uint32_t default_unit_job_id;
/* Data specific to the Automount subsystem */
int dev_autofs_fd;
/* Data specific to the cgroup subsystem */
Hashmap *cgroup_unit;
CGroupControllerMask cgroup_supported;
char *cgroup_root;
int gc_marker;
unsigned n_in_gc_queue;
/* Make sure the user cannot accidentally unmount our cgroup
* file system */
int pin_cgroupfs_fd;
/* Flags */
SystemdRunningAs running_as;
ManagerExitCode exit_code:5;
bool dispatching_load_queue:1;
bool dispatching_run_queue:1;
bool dispatching_dbus_queue:1;
bool taint_usr:1;
bool show_status;
bool confirm_spawn;
bool no_console_output;
ExecOutput default_std_output, default_std_error;
struct rlimit *rlimit[RLIMIT_NLIMITS];
/* non-zero if we are reloading or reexecuting, */
int n_reloading;
unsigned n_installed_jobs;
unsigned n_failed_jobs;
/* Jobs in progress watching */
unsigned n_running_jobs;
unsigned n_on_console;
unsigned jobs_in_progress_iteration;
/* Type=idle pipes */
int idle_pipe[4];
char *switch_root;
char *switch_root_init;
/* This maps all possible path prefixes to the units needing
* them. It's a hashmap with a path string as key and a Set as
* value where Unit objects are contained. */
Hashmap *units_requiring_mounts_for;
};
int manager_new(SystemdRunningAs running_as, bool reexecuting, Manager **m);
void manager_free(Manager *m);
int manager_enumerate(Manager *m);
int manager_coldplug(Manager *m);
int manager_startup(Manager *m, FILE *serialization, FDSet *fds);
Job *manager_get_job(Manager *m, uint32_t id);
Unit *manager_get_unit(Manager *m, const char *name);
int manager_get_unit_by_path(Manager *m, const char *path, const char *suffix, Unit **_found);
int manager_get_job_from_dbus_path(Manager *m, const char *s, Job **_j);
int manager_load_unit_prepare(Manager *m, const char *name, const char *path, DBusError *e, Unit **_ret);
int manager_load_unit(Manager *m, const char *name, const char *path, DBusError *e, Unit **_ret);
int manager_load_unit_from_dbus_path(Manager *m, const char *s, DBusError *e, Unit **_u);
int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool force, DBusError *e, Job **_ret);
int manager_add_job_by_name(Manager *m, JobType type, const char *name, JobMode mode, bool force, DBusError *e, Job **_ret);
void manager_dump_units(Manager *s, FILE *f, const char *prefix);
void manager_dump_jobs(Manager *s, FILE *f, const char *prefix);
void manager_clear_jobs(Manager *m);
unsigned manager_dispatch_load_queue(Manager *m);
unsigned manager_dispatch_run_queue(Manager *m);
unsigned manager_dispatch_dbus_queue(Manager *m);
int manager_environment_add(Manager *m, char **environment);
int manager_set_default_rlimits(Manager *m, struct rlimit **default_rlimit);
int manager_loop(Manager *m);
void manager_dispatch_bus_name_owner_changed(Manager *m, const char *name, const char* old_owner, const char *new_owner);
void manager_dispatch_bus_query_pid_done(Manager *m, const char *name, pid_t pid);
int manager_open_serialization(Manager *m, FILE **_f);
int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool switching_root);
int manager_deserialize(Manager *m, FILE *f, FDSet *fds);
int manager_distribute_fds(Manager *m, FDSet *fds);
int manager_reload(Manager *m);
bool manager_is_reloading_or_reexecuting(Manager *m) _pure_;
void manager_reset_failed(Manager *m);
void manager_send_unit_audit(Manager *m, Unit *u, int type, bool success);
void manager_send_unit_plymouth(Manager *m, Unit *u);
bool manager_unit_inactive_or_pending(Manager *m, const char *name);
void manager_check_finished(Manager *m);
void manager_run_generators(Manager *m);
void manager_undo_generators(Manager *m);
void manager_recheck_journal(Manager *m);
void manager_set_show_status(Manager *m, bool b);
void manager_status_printf(Manager *m, bool ephemeral, const char *status, const char *format, ...) _printf_attr_(4,5);
Set *manager_get_units_requiring_mounts_for(Manager *m, const char *path);
void watch_init(Watch *w);
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