![Lennart Poettering](/assets/img/avatar_default.png)
This replaces the dependencies Set* objects by Hashmap* objects, where the key is the depending Unit, and the value is a bitmask encoding why the specific dependency was created. The bitmask contains a number of different, defined bits, that indicate why dependencies exist, for example whether they are created due to explicitly configured deps in files, by udev rules or implicitly. Note that memory usage is not increased by this change, even though we store more information, as we manage to encode the bit mask inside the value pointer each Hashmap entry contains. Why this all? When we know how a dependency came to be, we can update dependencies correctly when a configuration source changes but others are left unaltered. Specifically: 1. We can fix UDEV_WANTS dependency generation: so far we kept adding dependencies configured that way, but if a device lost such a dependency we couldn't them again as there was no scheme for removing of dependencies in place. 2. We can implement "pin-pointed" reload of unit files. If we know what dependencies were created as result of configuration in a unit file, then we know what to flush out when we want to reload it. 3. It's useful for debugging: "systemd-analyze dump" now shows this information, helping substantially with understanding how systemd's dependency tree came to be the way it came to be.
362 lines
9.4 KiB
C
362 lines
9.4 KiB
C
/***
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This file is part of systemd.
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Copyright 2013 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include "alloc-util.h"
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#include "dbus-slice.h"
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#include "log.h"
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#include "slice.h"
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#include "special.h"
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#include "string-util.h"
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#include "strv.h"
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#include "unit-name.h"
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#include "unit.h"
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static const UnitActiveState state_translation_table[_SLICE_STATE_MAX] = {
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[SLICE_DEAD] = UNIT_INACTIVE,
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[SLICE_ACTIVE] = UNIT_ACTIVE
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};
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static void slice_init(Unit *u) {
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assert(u);
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assert(u->load_state == UNIT_STUB);
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u->ignore_on_isolate = true;
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}
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static void slice_set_state(Slice *t, SliceState state) {
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SliceState old_state;
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assert(t);
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old_state = t->state;
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t->state = state;
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if (state != old_state)
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log_debug("%s changed %s -> %s",
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UNIT(t)->id,
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slice_state_to_string(old_state),
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slice_state_to_string(state));
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unit_notify(UNIT(t), state_translation_table[old_state], state_translation_table[state], true);
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}
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static int slice_add_parent_slice(Slice *s) {
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char *a, *dash;
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Unit *parent;
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int r;
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assert(s);
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if (UNIT_ISSET(UNIT(s)->slice))
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return 0;
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if (unit_has_name(UNIT(s), SPECIAL_ROOT_SLICE))
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return 0;
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a = strdupa(UNIT(s)->id);
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dash = strrchr(a, '-');
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if (dash)
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strcpy(dash, ".slice");
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else
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a = (char*) SPECIAL_ROOT_SLICE;
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r = manager_load_unit(UNIT(s)->manager, a, NULL, NULL, &parent);
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if (r < 0)
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return r;
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unit_ref_set(&UNIT(s)->slice, parent);
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return 0;
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}
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static int slice_add_default_dependencies(Slice *s) {
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int r;
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assert(s);
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if (!UNIT(s)->default_dependencies)
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return 0;
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/* Make sure slices are unloaded on shutdown */
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r = unit_add_two_dependencies_by_name(
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UNIT(s),
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UNIT_BEFORE, UNIT_CONFLICTS,
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SPECIAL_SHUTDOWN_TARGET, NULL, true, UNIT_DEPENDENCY_DEFAULT);
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if (r < 0)
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return r;
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return 0;
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}
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static int slice_verify(Slice *s) {
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_cleanup_free_ char *parent = NULL;
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int r;
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assert(s);
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if (UNIT(s)->load_state != UNIT_LOADED)
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return 0;
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if (!slice_name_is_valid(UNIT(s)->id)) {
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log_unit_error(UNIT(s), "Slice name %s is not valid. Refusing.", UNIT(s)->id);
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return -EINVAL;
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}
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r = slice_build_parent_slice(UNIT(s)->id, &parent);
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if (r < 0)
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return log_unit_error_errno(UNIT(s), r, "Failed to determine parent slice: %m");
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if (parent ? !unit_has_name(UNIT_DEREF(UNIT(s)->slice), parent) : UNIT_ISSET(UNIT(s)->slice)) {
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log_unit_error(UNIT(s), "Located outside of parent slice. Refusing.");
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return -EINVAL;
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}
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return 0;
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}
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static int slice_load_root_slice(Unit *u) {
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assert(u);
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if (!unit_has_name(u, SPECIAL_ROOT_SLICE))
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return 0;
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u->perpetual = true;
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/* The root slice is a bit special. For example it is always running and cannot be terminated. Because of its
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* special semantics we synthesize it here, instead of relying on the unit file on disk. */
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u->default_dependencies = false;
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u->ignore_on_isolate = true;
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if (!u->description)
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u->description = strdup("Root Slice");
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if (!u->documentation)
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u->documentation = strv_new("man:systemd.special(7)", NULL);
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return 1;
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}
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static int slice_load(Unit *u) {
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Slice *s = SLICE(u);
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int r;
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assert(s);
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assert(u->load_state == UNIT_STUB);
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r = slice_load_root_slice(u);
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if (r < 0)
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return r;
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r = unit_load_fragment_and_dropin_optional(u);
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if (r < 0)
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return r;
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/* This is a new unit? Then let's add in some extras */
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if (u->load_state == UNIT_LOADED) {
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r = unit_patch_contexts(u);
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if (r < 0)
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return r;
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r = slice_add_parent_slice(s);
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if (r < 0)
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return r;
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r = slice_add_default_dependencies(s);
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if (r < 0)
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return r;
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}
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return slice_verify(s);
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}
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static int slice_coldplug(Unit *u) {
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Slice *t = SLICE(u);
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assert(t);
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assert(t->state == SLICE_DEAD);
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if (t->deserialized_state != t->state)
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slice_set_state(t, t->deserialized_state);
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return 0;
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}
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static void slice_dump(Unit *u, FILE *f, const char *prefix) {
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Slice *t = SLICE(u);
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assert(t);
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assert(f);
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fprintf(f,
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"%sSlice State: %s\n",
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prefix, slice_state_to_string(t->state));
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cgroup_context_dump(&t->cgroup_context, f, prefix);
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}
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static int slice_start(Unit *u) {
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Slice *t = SLICE(u);
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int r;
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assert(t);
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assert(t->state == SLICE_DEAD);
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r = unit_acquire_invocation_id(u);
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if (r < 0)
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return r;
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(void) unit_realize_cgroup(u);
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(void) unit_reset_cpu_accounting(u);
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(void) unit_reset_ip_accounting(u);
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slice_set_state(t, SLICE_ACTIVE);
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return 1;
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}
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static int slice_stop(Unit *u) {
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Slice *t = SLICE(u);
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assert(t);
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assert(t->state == SLICE_ACTIVE);
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/* We do not need to destroy the cgroup explicitly,
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* unit_notify() will do that for us anyway. */
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slice_set_state(t, SLICE_DEAD);
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return 1;
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}
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static int slice_kill(Unit *u, KillWho who, int signo, sd_bus_error *error) {
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return unit_kill_common(u, who, signo, -1, -1, error);
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}
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static int slice_serialize(Unit *u, FILE *f, FDSet *fds) {
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Slice *s = SLICE(u);
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assert(s);
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assert(f);
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assert(fds);
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unit_serialize_item(u, f, "state", slice_state_to_string(s->state));
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return 0;
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}
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static int slice_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
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Slice *s = SLICE(u);
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assert(u);
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assert(key);
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assert(value);
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assert(fds);
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if (streq(key, "state")) {
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SliceState state;
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state = slice_state_from_string(value);
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if (state < 0)
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log_debug("Failed to parse state value %s", value);
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else
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s->deserialized_state = state;
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} else
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log_debug("Unknown serialization key '%s'", key);
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return 0;
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}
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_pure_ static UnitActiveState slice_active_state(Unit *u) {
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assert(u);
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return state_translation_table[SLICE(u)->state];
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}
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_pure_ static const char *slice_sub_state_to_string(Unit *u) {
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assert(u);
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return slice_state_to_string(SLICE(u)->state);
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}
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static void slice_enumerate(Manager *m) {
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Unit *u;
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int r;
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assert(m);
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u = manager_get_unit(m, SPECIAL_ROOT_SLICE);
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if (!u) {
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r = unit_new_for_name(m, sizeof(Slice), SPECIAL_ROOT_SLICE, &u);
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if (r < 0) {
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log_error_errno(r, "Failed to allocate the special " SPECIAL_ROOT_SLICE " unit: %m");
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return;
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}
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}
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u->perpetual = true;
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SLICE(u)->deserialized_state = SLICE_ACTIVE;
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unit_add_to_load_queue(u);
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unit_add_to_dbus_queue(u);
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}
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const UnitVTable slice_vtable = {
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.object_size = sizeof(Slice),
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.cgroup_context_offset = offsetof(Slice, cgroup_context),
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.sections =
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"Unit\0"
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"Slice\0"
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"Install\0",
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.private_section = "Slice",
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.can_transient = true,
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.init = slice_init,
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.load = slice_load,
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.coldplug = slice_coldplug,
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.dump = slice_dump,
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.start = slice_start,
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.stop = slice_stop,
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.kill = slice_kill,
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.serialize = slice_serialize,
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.deserialize_item = slice_deserialize_item,
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.active_state = slice_active_state,
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.sub_state_to_string = slice_sub_state_to_string,
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.bus_vtable = bus_slice_vtable,
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.bus_set_property = bus_slice_set_property,
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.bus_commit_properties = bus_slice_commit_properties,
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.enumerate = slice_enumerate,
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.status_message_formats = {
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.finished_start_job = {
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[JOB_DONE] = "Created slice %s.",
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},
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.finished_stop_job = {
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[JOB_DONE] = "Removed slice %s.",
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},
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},
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};
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