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job: use a lookup table for merging of job types

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It is easier to see what job_type_merge() is doing when the merging
rules are written in the form of a table.

job_type_is_superset() contained redundant information. It can be
simplified to a simple rule: Type A is a superset of B iff merging A
with B gives A.

Two job types are conflicting iff they are not mergeable.

Make job_type_lookup_merge() the core function to decide the type
merging. All other job_type_*() are just short wrappers around it.
They can be inline.

test-job-type gives the same results as before.
btw, the systemd binary is smaller by almost 1 KB.
This commit is contained in:
Michal Schmidt 2012-04-05 08:34:05 +02:00
parent b8217b7bd5
commit 348e27fedf
2 changed files with 62 additions and 94 deletions
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127
src/job.c
View File

@ -164,100 +164,47 @@ bool job_is_anchor(Job *j) {
return false;
}
static bool types_match(JobType a, JobType b, JobType c, JobType d) {
return
(a == c && b == d) ||
(a == d && b == c);
}
/*
* Merging is commutative, so imagine the matrix as symmetric. We store only
* its lower triangle to avoid duplication. We don't store the main diagonal,
* because A merged with A is simply A.
*
* Merging is associative! A merged with B merged with C is the same as
* A merged with C merged with B.
*
* Mergeability is transitive! If A can be merged with B and B with C then
* A also with C.
*
* Also, if A merged with B cannot be merged with C, then either A or B cannot
* be merged with C either.
*/
static const JobType job_merging_table[] = {
/* What \ With * JOB_START JOB_VERIFY_ACTIVE JOB_STOP JOB_RELOAD JOB_RELOAD_OR_START JOB_RESTART JOB_TRY_RESTART */
/************************************************************************************************************************************/
/*JOB_START */
/*JOB_VERIFY_ACTIVE */ JOB_START,
/*JOB_STOP */ -1, -1,
/*JOB_RELOAD */ JOB_RELOAD_OR_START, JOB_RELOAD, -1,
/*JOB_RELOAD_OR_START*/ JOB_RELOAD_OR_START, JOB_RELOAD_OR_START, -1, JOB_RELOAD_OR_START,
/*JOB_RESTART */ JOB_RESTART, JOB_RESTART, -1, JOB_RESTART, JOB_RESTART,
/*JOB_TRY_RESTART */ JOB_RESTART, JOB_TRY_RESTART, -1, JOB_TRY_RESTART, JOB_RESTART, JOB_RESTART,
};
int job_type_merge(JobType *a, JobType b) {
if (*a == b)
return 0;
/* Merging is associative! a merged with b merged with c is
* the same as a merged with c merged with b. */
/* Mergeability is transitive! if a can be merged with b and b
* with c then a also with c */
/* Also, if a merged with b cannot be merged with c, then
* either a or b cannot be merged with c either */
if (types_match(*a, b, JOB_START, JOB_VERIFY_ACTIVE))
*a = JOB_START;
else if (types_match(*a, b, JOB_START, JOB_RELOAD) ||
types_match(*a, b, JOB_START, JOB_RELOAD_OR_START) ||
types_match(*a, b, JOB_VERIFY_ACTIVE, JOB_RELOAD_OR_START) ||
types_match(*a, b, JOB_RELOAD, JOB_RELOAD_OR_START))
*a = JOB_RELOAD_OR_START;
else if (types_match(*a, b, JOB_START, JOB_RESTART) ||
types_match(*a, b, JOB_START, JOB_TRY_RESTART) ||
types_match(*a, b, JOB_VERIFY_ACTIVE, JOB_RESTART) ||
types_match(*a, b, JOB_RELOAD, JOB_RESTART) ||
types_match(*a, b, JOB_RELOAD_OR_START, JOB_RESTART) ||
types_match(*a, b, JOB_RELOAD_OR_START, JOB_TRY_RESTART) ||
types_match(*a, b, JOB_RESTART, JOB_TRY_RESTART))
*a = JOB_RESTART;
else if (types_match(*a, b, JOB_VERIFY_ACTIVE, JOB_RELOAD))
*a = JOB_RELOAD;
else if (types_match(*a, b, JOB_VERIFY_ACTIVE, JOB_TRY_RESTART) ||
types_match(*a, b, JOB_RELOAD, JOB_TRY_RESTART))
*a = JOB_TRY_RESTART;
else
return -EEXIST;
return 0;
}
bool job_type_is_mergeable(JobType a, JobType b) {
return job_type_merge(&a, b) >= 0;
}
bool job_type_is_superset(JobType a, JobType b) {
/* Checks whether operation a is a "superset" of b in its
* actions */
if (a == b)
return true;
switch (a) {
case JOB_START:
return b == JOB_VERIFY_ACTIVE;
case JOB_RELOAD:
return
b == JOB_VERIFY_ACTIVE;
case JOB_RELOAD_OR_START:
return
b == JOB_RELOAD ||
b == JOB_START ||
b == JOB_VERIFY_ACTIVE;
case JOB_RESTART:
return
b == JOB_START ||
b == JOB_VERIFY_ACTIVE ||
b == JOB_RELOAD ||
b == JOB_RELOAD_OR_START ||
b == JOB_TRY_RESTART;
case JOB_TRY_RESTART:
return
b == JOB_VERIFY_ACTIVE ||
b == JOB_RELOAD;
default:
return false;
}
}
bool job_type_is_conflicting(JobType a, JobType b) {
JobType job_type_lookup_merge(JobType a, JobType b) {
assert_cc(ELEMENTSOF(job_merging_table) == _JOB_TYPE_MAX * (_JOB_TYPE_MAX - 1) / 2);
assert(a >= 0 && a < _JOB_TYPE_MAX);
assert(b >= 0 && b < _JOB_TYPE_MAX);
return (a == JOB_STOP) != (b == JOB_STOP);
if (a == b)
return a;
if (a < b) {
JobType tmp = a;
a = b;
b = tmp;
}
return job_merging_table[(a - 1) * a / 2 + b];
}
bool job_type_is_redundant(JobType a, UnitActiveState b) {

29
src/job.h
View File

@ -24,6 +24,7 @@
#include <stdbool.h>
#include <inttypes.h>
#include <errno.h>
typedef struct Job Job;
typedef struct JobDependency JobDependency;
@ -37,6 +38,7 @@ typedef enum JobResult JobResult;
#include "hashmap.h"
#include "list.h"
/* Be careful when changing the job types! Adjust job_merging_table[] accordingly! */
enum JobType {
JOB_START, /* if a unit does not support being started, we'll just wait until it becomes active */
JOB_VERIFY_ACTIVE,
@ -145,10 +147,29 @@ bool job_is_anchor(Job *j);
int job_merge(Job *j, Job *other);
int job_type_merge(JobType *a, JobType b);
bool job_type_is_mergeable(JobType a, JobType b);
bool job_type_is_superset(JobType a, JobType b);
bool job_type_is_conflicting(JobType a, JobType b);
JobType job_type_lookup_merge(JobType a, JobType b);
static inline int job_type_merge(JobType *a, JobType b) {
JobType t = job_type_lookup_merge(*a, b);
if (t < 0)
return -EEXIST;
*a = t;
return 0;
}
static inline bool job_type_is_mergeable(JobType a, JobType b) {
return job_type_lookup_merge(a, b) >= 0;
}
static inline bool job_type_is_conflicting(JobType a, JobType b) {
return !job_type_is_mergeable(a, b);
}
static inline bool job_type_is_superset(JobType a, JobType b) {
/* Checks whether operation a is a "superset" of b in its actions */
return a == job_type_lookup_merge(a, b);
}
bool job_type_is_redundant(JobType a, UnitActiveState b);
bool job_is_runnable(Job *j);