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Systemd/manager.c

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/*-*- Mode: C; c-basic-offset: 8 -*-*/
#include <assert.h>
#include <errno.h>
#include <string.h>
#include "manager.h"
#include "hashmap.h"
#include "macro.h"
#include "strv.h"
#include "log.h"
Manager* manager_new(void) {
Manager *m;
if (!(m = new0(Manager, 1)))
return NULL;
if (!(m->names = hashmap_new(string_hash_func, string_compare_func)))
goto fail;
if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
goto fail;
if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
goto fail;
return m;
fail:
manager_free(m);
return NULL;
}
void manager_free(Manager *m) {
Name *n;
Job *j;
assert(m);
while ((n = hashmap_first(m->names)))
name_free(n);
while ((j = hashmap_steal_first(m->transaction_jobs)))
job_free(j);
hashmap_free(m->names);
hashmap_free(m->jobs);
hashmap_free(m->transaction_jobs);
free(m);
}
static void transaction_delete_job(Manager *m, Job *j) {
assert(m);
assert(j);
/* Deletes one job from the transaction */
manager_transaction_unlink_job(m, j);
if (!j->linked)
job_free(j);
}
static void transaction_delete_name(Manager *m, Name *n) {
Job *j;
/* Deletes all jobs associated with a certain name from the
* transaction */
while ((j = hashmap_get(m->transaction_jobs, n)))
transaction_delete_job(m, j);
}
static void transaction_abort(Manager *m) {
Job *j;
assert(m);
while ((j = hashmap_first(m->transaction_jobs)))
if (j->linked)
transaction_delete_job(m, j);
else
job_free(j);
assert(hashmap_isempty(m->transaction_jobs));
assert(!m->transaction_anchor);
}
static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
JobDependency *l;
assert(m);
/* A recursive sweep through the graph that marks all names
* that matter to the anchor job, i.e. are directly or
* indirectly a dependency of the anchor job via paths that
* are fully marked as mattering. */
for (l = j ? j->subject_list : m->transaction_anchor; l; l = l->subject_next) {
/* This link does not matter */
if (!l->matters)
continue;
/* This name has already been marked */
if (l->object->generation == generation)
continue;
l->object->matters_to_anchor = true;
l->object->generation = generation;
transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
}
}
static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
JobDependency *l, *last;
assert(j);
assert(other);
assert(j->name == other->name);
assert(!j->linked);
/* Merges 'other' into 'j' and then deletes j. */
j->type = t;
j->state = JOB_WAITING;
j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
/* Patch us in as new owner of the JobDependency objects */
last = NULL;
for (l = other->subject_list; l; l = l->subject_next) {
assert(l->subject == other);
l->subject = j;
last = l;
}
/* Merge both lists */
if (last) {
last->subject_next = j->subject_list;
if (j->subject_list)
j->subject_list->subject_prev = last;
j->subject_list = other->subject_list;
}
/* Patch us in as new owner of the JobDependency objects */
last = NULL;
for (l = other->object_list; l; l = l->object_next) {
assert(l->object == other);
l->object = j;
last = l;
}
/* Merge both lists */
if (last) {
last->object_next = j->object_list;
if (j->object_list)
j->object_list->object_prev = last;
j->object_list = other->object_list;
}
/* Kill the other job */
other->subject_list = NULL;
other->object_list = NULL;
transaction_delete_job(m, other);
}
static int delete_one_unmergable_job(Manager *m, Job *j) {
Job *k;
assert(j);
/* Tries to delete one item in the linked list
* j->transaction_next->transaction_next->... that conflicts
* whith another one, in an attempt to make an inconsistent
* transaction work. */
/* We rely here on the fact that if a merged with b does not
* merge with c, either a or b merge with c neither */
for (; j; j = j->transaction_next)
for (k = j->transaction_next; k; k = k->transaction_next) {
Job *d;
/* Is this one mergeable? Then skip it */
if (job_type_mergeable(j->type, k->type))
continue;
/* Ok, we found two that conflict, let's see if we can
* drop one of them */
if (!j->matters_to_anchor)
d = j;
else if (!k->matters_to_anchor)
d = k;
else
return -ENOEXEC;
/* Ok, we can drop one, so let's do so. */
log_debug("Try to fix job merging by deleting job %s", name_id(d->name));
transaction_delete_job(m, d);
return 0;
}
return -EINVAL;
}
static int transaction_merge_jobs(Manager *m) {
Job *j;
void *state;
int r;
assert(m);
/* First step, check whether any of the jobs for one specific
* task conflict. If so, try to drop one of them. */
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
JobType t;
Job *k;
t = j->type;
for (k = j->transaction_next; k; k = k->transaction_next) {
if ((r = job_type_merge(&t, k->type)) >= 0)
continue;
/* OK, we could not merge all jobs for this
* action. Let's see if we can get rid of one
* of them */
if ((r = delete_one_unmergable_job(m, j)) >= 0)
/* Ok, we managed to drop one, now
* let's ask our callers to call us
* again after garbage collecting */
return -EAGAIN;
/* We couldn't merge anything. Failure */
return r;
}
}
/* Second step, merge the jobs. */
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
JobType t = j->type;
Job *k;
for (k = j->transaction_next; k; k = k->transaction_next)
assert_se(job_type_merge(&t, k->type) == 0);
while ((k = j->transaction_next)) {
if (j->linked) {
transaction_merge_and_delete_job(m, k, j, t);
j = k;
} else
transaction_merge_and_delete_job(m, j, k, t);
}
assert(!j->transaction_next);
assert(!j->transaction_prev);
}
return 0;
}
static bool name_matters_to_anchor(Name *n, Job *j) {
assert(n);
assert(!j->transaction_prev);
/* Checks whether at least one of the jobs for this name
* matters to the anchor. */
for (; j; j = j->transaction_next)
if (j->matters_to_anchor)
return true;
return false;
}
static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
void *state;
Name *n;
int r;
assert(m);
assert(j);
assert(!j->transaction_prev);
/* Does a recursive sweep through the ordering graph, looking
* for a cycle. If we find cycle we try to break it. */
/* Did we find a cycle? */
if (j->marker && j->generation == generation) {
Job *k;
/* So, we already have been here. We have a
* cycle. Let's try to break it. We go backwards in
* our path and try to find a suitable job to
* remove. We use the marker to find our way back,
* since smart how we are we stored our way back in
* there. */
for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
if (!k->linked &&
!name_matters_to_anchor(k->name, k)) {
/* Ok, we can drop this one, so let's
* do so. */
log_debug("Breaking order cycle by deleting job %s", name_id(k->name));
transaction_delete_name(m, k->name);
return -EAGAIN;
}
/* Check if this in fact was the beginning of
* the cycle */
if (k == j)
break;
}
return -ENOEXEC;
}
/* Make the marker point to where we come from, so that we can
* find our way backwards if we want to break a cycle */
j->marker = from;
j->generation = generation;
/* We assume that the the dependencies are bidirectional, and
* hence can ignore NAME_AFTER */
SET_FOREACH(n, j->name->meta.dependencies[NAME_BEFORE], state) {
Job *o;
/* Is there a job for this name? */
if (!(o = hashmap_get(m->transaction_jobs, n)))
/* Ok, there is no job for this in the
* transaction, but maybe there is already one
* running? */
if (!(o = n->meta.job))
continue;
if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
return r;
}
return 0;
}
static int transaction_verify_order(Manager *m, unsigned *generation) {
Job *j;
int r;
void *state;
assert(m);
assert(generation);
/* Check if the ordering graph is cyclic. If it is, try to fix
* that up by dropping one of the jobs. */
HASHMAP_FOREACH(j, m->transaction_jobs, state)
if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
return r;
return 0;
}
static void transaction_collect_garbage(Manager *m) {
bool again;
assert(m);
/* Drop jobs that are not required by any other job */
do {
void *state;
Job *j;
again = false;
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
if (j->object_list)
continue;
log_debug("Garbage collecting job %s", name_id(j->name));
transaction_delete_job(m, j);
again = true;
break;
}
} while (again);
}
static int transaction_is_destructive(Manager *m, JobMode mode) {
void *state;
Job *j;
assert(m);
/* Checks whether applying this transaction means that
* existing jobs would be replaced */
HASHMAP_FOREACH(j, m->transaction_jobs, state)
if (j->name->meta.job &&
j->name->meta.job != j &&
!job_type_is_superset(j->type, j->name->meta.job->type))
return -EEXIST;
return 0;
}
static int transaction_apply(Manager *m, JobMode mode) {
void *state;
Job *j;
int r;
/* Moves the transaction jobs to the set of active jobs */
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
if (j->linked)
continue;
if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
goto rollback;
}
while ((j = hashmap_steal_first(m->transaction_jobs))) {
if (j->linked)
continue;
if (j->name->meta.job)
job_free(j->name->meta.job);
j->name->meta.job = j;
j->linked = true;
/* We're fully installed. Now let's free data we don't
* need anymore. */
assert(!j->transaction_next);
assert(!j->transaction_prev);
while (j->subject_list)
job_dependency_free(j->subject_list);
while (j->object_list)
job_dependency_free(j->object_list);
}
m->transaction_anchor = NULL;
return 0;
rollback:
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
if (j->linked)
continue;
hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
}
return r;
}
static int transaction_activate(Manager *m, JobMode mode) {
int r;
unsigned generation = 1;
assert(m);
/* This applies the changes recorded in transaction_jobs to
* the actual list of jobs, if possible. */
/* First step: figure out which jobs matter */
transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
for (;;) {
/* Second step: Let's remove unneeded jobs that might
* be lurking. */
transaction_collect_garbage(m);
/* Third step: verify order makes sense and correct
* cycles if necessary and possible */
if ((r = transaction_verify_order(m, &generation)) >= 0)
break;
if (r != -EAGAIN)
goto rollback;
/* Let's see if the resulting transaction ordering
* graph is still cyclic... */
}
for (;;) {
/* Fourth step: let's drop unmergable entries if
* necessary and possible, merge entries we can
* merge */
if ((r = transaction_merge_jobs(m)) >= 0)
break;
if (r != -EAGAIN)
goto rollback;
/* Fifth step: an entry got dropped, let's garbage
* collect its dependencies. */
transaction_collect_garbage(m);
/* Let's see if the resulting transaction still has
* unmergable entries ... */
}
/* Sith step: check whether we can actually apply this */
if (mode == JOB_FAIL)
if ((r = transaction_is_destructive(m, mode)) < 0)
goto rollback;
/* Seventh step: apply changes */
if ((r = transaction_apply(m, mode)) < 0)
goto rollback;
assert(hashmap_isempty(m->transaction_jobs));
assert(!m->transaction_anchor);
return 0;
rollback:
transaction_abort(m);
return r;
}
static Job* transaction_add_one_job(Manager *m, JobType type, Name *name, bool *is_new) {
Job *j, *f;
int r;
assert(m);
assert(name);
/* Looks for an axisting prospective job and returns that. If
* it doesn't exist it is created and added to the prospective
* jobs list. */
f = hashmap_get(m->transaction_jobs, name);
for (j = f; j; j = j->transaction_next) {
assert(j->name == name);
if (j->type == type) {
if (is_new)
*is_new = false;
return j;
}
}
if (name->meta.job && name->meta.job->type == type)
j = name->meta.job;
else if (!(j = job_new(m, type, name)))
return NULL;
if ((r = hashmap_replace(m->transaction_jobs, name, j)) < 0) {
job_free(j);
return NULL;
}
j->transaction_next = f;
if (f)
f->transaction_prev = j;
j->generation = 0;
j->marker = NULL;
j->matters_to_anchor = false;
if (is_new)
*is_new = true;
return j;
}
void manager_transaction_unlink_job(Manager *m, Job *j) {
assert(m);
assert(j);
if (j->transaction_prev)
j->transaction_prev->transaction_next = j->transaction_next;
else if (j->transaction_next)
hashmap_replace(m->transaction_jobs, j->name, j->transaction_next);
else
hashmap_remove_value(m->transaction_jobs, j->name, j);
if (j->transaction_next)
j->transaction_next->transaction_prev = j->transaction_prev;
j->transaction_prev = j->transaction_next = NULL;
while (j->subject_list)
job_dependency_free(j->subject_list);
while (j->object_list) {
Job *other = j->object_list->matters ? j->object_list->subject : NULL;
job_dependency_free(j->object_list);
if (other) {
log_debug("Deleting job %s as dependency of job %s", name_id(other->name), name_id(j->name));
transaction_delete_job(m, other);
}
}
}
static int transaction_add_job_and_dependencies(Manager *m, JobType type, Name *name, Job *by, bool matters, bool force, Job **_ret) {
Job *ret;
void *state;
Name *dep;
int r;
bool is_new;
assert(m);
assert(type < _JOB_TYPE_MAX);
assert(name);
if (name->meta.state != NAME_LOADED)
return -EINVAL;
/* First add the job. */
if (!(ret = transaction_add_one_job(m, type, name, &is_new)))
return -ENOMEM;
/* Then, add a link to the job. */
if (!job_dependency_new(by, ret, matters))
return -ENOMEM;
if (is_new) {
/* Finally, recursively add in all dependencies. */
if (type == JOB_START || type == JOB_RELOAD_OR_START) {
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUIRES], state)
if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0)
goto fail;
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUIRES], state)
if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0)
goto fail;
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_WANTS], state)
if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0)
goto fail;
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUISITE], state)
if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_STARTED, dep, ret, true, force, NULL)) < 0)
goto fail;
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_SOFT_REQUISITE], state)
if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_STARTED, dep, ret, !force, force, NULL)) < 0)
goto fail;
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_CONFLICTS], state)
if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0)
goto fail;
} else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
SET_FOREACH(dep, ret->name->meta.dependencies[NAME_REQUIRED_BY], state)
if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0)
goto fail;
}
/* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
}
return 0;
fail:
return r;
}
int manager_add_job(Manager *m, JobType type, Name *name, JobMode mode, bool force, Job **_ret) {
int r;
Job *ret;
assert(m);
assert(type < _JOB_TYPE_MAX);
assert(name);
assert(mode < _JOB_MODE_MAX);
if ((r = transaction_add_job_and_dependencies(m, type, name, NULL, true, force, &ret))) {
transaction_abort(m);
return r;
}
if ((r = transaction_activate(m, mode)) < 0)
return r;
if (_ret)
*_ret = ret;
return 0;
}
Job *manager_get_job(Manager *m, uint32_t id) {
assert(m);
return hashmap_get(m->jobs, UINT32_TO_PTR(id));
}
Name *manager_get_name(Manager *m, const char *name) {
assert(m);
assert(name);
return hashmap_get(m->names, name);
}
static int dispatch_load_queue(Manager *m) {
Meta *meta;
assert(m);
/* Make sure we are not run recursively */
if (m->dispatching_load_queue)
return 0;
m->dispatching_load_queue = true;
/* Dispatches the load queue. Takes a name from the queue and
* tries to load its data until the queue is empty */
while ((meta = m->load_queue)) {
name_load(NAME(meta));
LIST_REMOVE(Meta, m->load_queue, meta);
}
m->dispatching_load_queue = false;
return 0;
}
int manager_load_name(Manager *m, const char *name, Name **_ret) {
Name *ret;
NameType t;
int r;
char *n;
assert(m);
assert(name);
assert(_ret);
if (!name_is_valid(name))
return -EINVAL;
/* This will load the service information files, but not actually
* start any services or anything */
if ((ret = manager_get_name(m, name)))
goto finish;
if ((t = name_type_from_string(name)) == _NAME_TYPE_INVALID)
return -EINVAL;
if (!(ret = name_new(m)))
return -ENOMEM;
ret->meta.type = t;
if (!(n = strdup(name))) {
name_free(ret);
return -ENOMEM;
}
if ((r = set_put(ret->meta.names, n)) < 0) {
name_free(ret);
free(n);
return r;
}
if ((r = name_link(ret)) < 0) {
name_free(ret);
return r;
}
/* At this point the new entry is created and linked. However,
* not loaded. Now load this entry and all its dependencies
* recursively */
dispatch_load_queue(m);
finish:
*_ret = ret;
return 0;
}
void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
void *state;
Job *j;
assert(s);
assert(f);
HASHMAP_FOREACH(j, s->jobs, state)
job_dump(j, f, prefix);
}
void manager_dump_names(Manager *s, FILE *f, const char *prefix) {
void *state;
Name *n;
const char *t;
assert(s);
assert(f);
HASHMAP_FOREACH_KEY(n, t, s->names, state)
if (name_id(n) == t)
name_dump(n, f, prefix);
}
void manager_clear_jobs(Manager *m) {
Job *j;
assert(m);
transaction_abort(m);
while ((j = hashmap_first(m->jobs)))
job_free(j);
}
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