feat(server): Remove premature caching optimizations (#454)

This was done without any measurements. Can add back
when this is really proved to improve performance.

judgels-backends/judgels-server-app/src/main/java/judgels/jerahmeel/chapter/ChapterStore.java

@@ -1,9 +1,5 @@
 package judgels.jerahmeel.chapter;
 
-import static judgels.jerahmeel.JerahmeelCacheUtils.getShortDuration;
-
-import com.github.benmanes.caffeine.cache.Caffeine;
-import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -31,30 +27,19 @@ public class ChapterStore {
     private final CourseChapterDao courseChapterDao;
     private final CourseDao courseDao;
 
-    private final LoadingCache<String, Chapter> chapterByJidCache;
-
     @Inject
     public ChapterStore(ChapterDao chapterDao, CourseChapterDao courseChapterDao, CourseDao courseDao) {
         this.chapterDao = chapterDao;
         this.courseChapterDao = courseChapterDao;
         this.courseDao = courseDao;
-
-        this.chapterByJidCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getChapterByJidUncached);
     }
 
     public List<Chapter> getChapters() {
         return Lists.transform(chapterDao.select().all(), ChapterStore::fromModel);
     }
 
     public Optional<Chapter> getChapterByJid(String chapterJid) {
-        return Optional.ofNullable(chapterByJidCache.get(chapterJid));
-    }
-
-    private Chapter getChapterByJidUncached(String chapterJid) {
-        return chapterDao.selectByJid(chapterJid).map(ChapterStore::fromModel).orElse(null);
+        return chapterDao.selectByJid(chapterJid).map(ChapterStore::fromModel);
     }
 
     public Map<String, ChapterInfo> getChapterInfosByJids(Set<String> chapterJids) {
@@ -113,8 +98,6 @@ public Chapter createChapter(ChapterCreateData data) {
 
     public Optional<Chapter> updateChapter(String chapterJid, ChapterUpdateData data) {
         return chapterDao.selectByJid(chapterJid).map(model -> {
-            chapterByJidCache.invalidate(chapterJid);
-
             data.getName().ifPresent(name -> model.name = name);
             return fromModel(chapterDao.update(model));
         });

judgels-backends/judgels-server-app/src/main/java/judgels/jerahmeel/course/CourseStore.java

@@ -1,9 +1,5 @@
 package judgels.jerahmeel.course;
 
-import static judgels.jerahmeel.JerahmeelCacheUtils.getShortDuration;
-
-import com.github.benmanes.caffeine.cache.Caffeine;
-import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.google.common.collect.Lists;
 import java.util.List;
 import java.util.Optional;
@@ -20,37 +16,17 @@
 public class CourseStore {
     private final CourseDao courseDao;
 
-    private final LoadingCache<String, Course> courseByJidCache;
-    private final LoadingCache<String, Course> courseBySlugCache;
-
     @Inject
     public CourseStore(CourseDao courseDao) {
         this.courseDao = courseDao;
-
-        this.courseByJidCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getCourseByJidUncached);
-        this.courseBySlugCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getCourseBySlugUncached);
     }
 
     public Optional<Course> getCourseByJid(String courseJid) {
-        return Optional.ofNullable(courseByJidCache.get(courseJid));
-    }
-
-    private Course getCourseByJidUncached(String courseJid) {
-        return courseDao.selectByJid(courseJid).map(CourseStore::fromModel).orElse(null);
+        return courseDao.selectByJid(courseJid).map(CourseStore::fromModel);
     }
 
     public Optional<Course> getCourseBySlug(String courseSlug) {
-        return Optional.ofNullable(courseBySlugCache.get(courseSlug));
-    }
-
-    private Course getCourseBySlugUncached(String courseSlug) {
-        return courseDao.selectBySlug(courseSlug).map(CourseStore::fromModel).orElse(null);
+        return courseDao.selectBySlug(courseSlug).map(CourseStore::fromModel);
     }
 
     public List<Course> getCourses() {
@@ -84,14 +60,6 @@ public Optional<Course> updateCourse(String courseJid, CourseUpdateData data) {
                 }
             }
 
-            courseByJidCache.invalidate(courseJid);
-            if (model.slug != null) {
-                courseBySlugCache.invalidate(model.slug);
-            }
-            if (data.getSlug().isPresent()) {
-                courseBySlugCache.invalidate(data.getSlug().get());
-            }
-
             data.getSlug().ifPresent(slug -> model.slug = slug);
             data.getName().ifPresent(name -> model.name = name);
             data.getDescription().ifPresent(description -> model.description = description);

judgels-backends/judgels-server-app/src/main/java/judgels/jerahmeel/hibernate/ProblemSetHibernateDao.java

@@ -1,6 +1,8 @@
 package judgels.jerahmeel.hibernate;
 
+import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import javax.inject.Inject;
 import judgels.jerahmeel.persistence.ProblemSetDao;
 import judgels.jerahmeel.persistence.ProblemSetModel;
@@ -33,6 +35,11 @@ public Optional<ProblemSetModel> selectBySlug(String problemSetSlug) {
                 .unique();
     }
 
+    @Override
+    public List<ProblemSetModel> selectAllBySlugs(Set<String> contestSlugs) {
+        return select().where(columnIn(ProblemSetModel_.slug, contestSlugs)).all();
+    }
+
     private static class ProblemSetHibernateQueryBuilder extends HibernateQueryBuilder<ProblemSetModel> implements ProblemSetQueryBuilder {
         ProblemSetHibernateQueryBuilder(Session currentSession) {
             super(currentSession, ProblemSetModel.class);

judgels-backends/judgels-server-app/src/main/java/judgels/jerahmeel/persistence/ProblemSetDao.java

@@ -1,13 +1,16 @@
 package judgels.jerahmeel.persistence;
 
+import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import judgels.persistence.JudgelsDao;
 import judgels.persistence.QueryBuilder;
 
 public interface ProblemSetDao extends JudgelsDao<ProblemSetModel> {
     ProblemSetQueryBuilder select();
 
     Optional<ProblemSetModel> selectBySlug(String problemSetSlug);
+    List<ProblemSetModel> selectAllBySlugs(Set<String> contestSlugs);
 
     interface ProblemSetQueryBuilder extends QueryBuilder<ProblemSetModel> {
         ProblemSetQueryBuilder whereArchiveIs(String archiveJid);

judgels-backends/judgels-server-app/src/main/java/judgels/jerahmeel/problemset/ProblemSetStore.java

@@ -1,9 +1,7 @@
 package judgels.jerahmeel.problemset;
 
-import static judgels.jerahmeel.JerahmeelCacheUtils.getShortDuration;
+import static java.util.stream.Collectors.toMap;
 
-import com.github.benmanes.caffeine.cache.Caffeine;
-import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -13,7 +11,6 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
-import java.util.stream.Collectors;
 import javax.inject.Inject;
 import judgels.jerahmeel.api.problemset.ProblemSet;
 import judgels.jerahmeel.api.problemset.ProblemSetCreateData;
@@ -38,10 +35,6 @@ public class ProblemSetStore {
     private final ProblemContestDao problemContestDao;
     private final ArchiveDao archiveDao;
 
-    private final LoadingCache<String, ProblemSet> problemSetByJidCache;
-    private final LoadingCache<String, ProblemSet> problemSetBySlugCache;
-    private final LoadingCache<String, ProblemSet> problemSetByContestJidCache;
-
     @Inject
     public ProblemSetStore(
             ProblemSetDao problemSetDao,
@@ -53,55 +46,31 @@ public ProblemSetStore(
         this.problemSetProblemDao = problemSetProblemDao;
         this.problemContestDao = problemContestDao;
         this.archiveDao = archiveDao;
-
-        this.problemSetByJidCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getProblemSetByJidUncached);
-        this.problemSetBySlugCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getProblemSetBySlugUncached);
-        this.problemSetByContestJidCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getProblemSetByContestJidUncached);
     }
 
     public Optional<ProblemSet> getProblemSetByJid(String problemSetJid) {
-        return Optional.ofNullable(problemSetByJidCache.get(problemSetJid));
-    }
-
-    private ProblemSet getProblemSetByJidUncached(String problemSetJid) {
-        return problemSetDao.selectByJid(problemSetJid).map(ProblemSetStore::fromModel).orElse(null);
+        return problemSetDao.selectByJid(problemSetJid).map(ProblemSetStore::fromModel);
     }
 
     public Optional<ProblemSet> getProblemSetBySlug(String problemSetSlug) {
-        return Optional.ofNullable(problemSetBySlugCache.get(problemSetSlug));
+        return problemSetDao.selectBySlug(problemSetSlug).map(ProblemSetStore::fromModel);
     }
 
     public Map<String, ProblemSet> getProblemSetsBySlugs(Set<String> problemSetSlugs) {
-        return problemSetBySlugCache.getAll(problemSetSlugs);
-    }
-
-    private ProblemSet getProblemSetBySlugUncached(String problemSetSlug) {
-        return problemSetDao.selectBySlug(problemSetSlug).map(ProblemSetStore::fromModel).orElse(null);
+        return problemSetDao.selectAllBySlugs(problemSetSlugs).stream().collect(toMap(
+                m -> m.slug, ProblemSetStore::fromModel));
     }
 
     public Optional<ProblemSet> getProblemSetByContestJid(String contestJid) {
-        return Optional.ofNullable(problemSetByContestJidCache.get(contestJid));
-    }
-
-    private ProblemSet getProblemSetByContestJidUncached(String contestJid) {
         for (ProblemContestModel pcm : problemContestDao.selectAllByContestJid(contestJid)) {
             for (ProblemSetProblemModel pspm : problemSetProblemDao.selectAllByProblemJid(pcm.problemJid)) {
                 Optional<ProblemSetModel> m = problemSetDao.selectByJid(pspm.problemSetJid);
                 if (m.isPresent()) {
-                    return fromModel(m.get());
+                    return Optional.of(fromModel(m.get()));
                 }
             }
         }
-        return null;
+        return Optional.empty();
     }
 
     public Page<ProblemSet> getProblemSets(Optional<String> archiveJid, Optional<String> nameFilter, int pageNumber, int pageSize) {
@@ -128,7 +97,7 @@ public Map<String, String> getProblemSetNamesByJids(Set<String> problemSetJids)
         return problemSetDao.selectByJids(problemSetJids)
                 .values()
                 .stream()
-                .collect(Collectors.toMap(
+                .collect(toMap(
                         c -> c.jid,
                         c -> c.name));
     }
@@ -185,13 +154,6 @@ public Optional<ProblemSet> updateProblemSet(String problemSetJid, ProblemSetUpd
                 model.archiveJid = archiveModel.get().jid;
             }
 
-            problemSetByJidCache.invalidate(problemSetJid);
-            if (model.slug != null) {
-                problemSetBySlugCache.invalidate(model.slug);
-            }
-            if (data.getSlug().isPresent()) {
-                problemSetBySlugCache.invalidate(data.getSlug().get());
-            }
 
             data.getSlug().ifPresent(slug -> model.slug = slug);
             data.getName().ifPresent(name -> model.name = name);

judgels-backends/judgels-server-app/src/main/java/judgels/uriel/contest/ContestStore.java

@@ -2,10 +2,7 @@
 
 import static java.time.temporal.ChronoUnit.MILLIS;
 import static java.util.stream.Collectors.toMap;
-import static judgels.uriel.UrielCacheUtils.getShortDuration;
 
-import com.github.benmanes.caffeine.cache.Caffeine;
-import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.google.common.collect.Lists;
 import java.time.Duration;
 import java.time.Instant;
@@ -53,9 +50,6 @@ public class ContestStore {
     private final ContestAnnouncementStore announcementStore;
     private final ContestClarificationStore clarificationStore;
 
-    private final LoadingCache<String, Contest> contestByJidCache;
-    private final LoadingCache<String, Contest> contestBySlugCache;
-
     @Inject
     public ContestStore(
             ContestDao contestDao,
@@ -75,19 +69,10 @@ public ContestStore(
         this.managerStore = managerStore;
         this.announcementStore = announcementStore;
         this.clarificationStore = clarificationStore;
-
-        this.contestByJidCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getContestByJidUncached);
-        this.contestBySlugCache = Caffeine.newBuilder()
-                .maximumSize(100)
-                .expireAfterWrite(getShortDuration())
-                .build(this::getContestBySlugUncached);
     }
 
     public Optional<Contest> getContestByJid(String contestJid) {
-        return Optional.ofNullable(contestByJidCache.get(contestJid));
+        return contestDao.selectByJid(contestJid).map(ContestStore::fromModel);
     }
 
     public Map<String, ContestInfo> getContestInfosByJids(Set<String> contestJids) {
@@ -103,16 +88,8 @@ public Map<String, ContestInfo> getContestInfosByJids(Set<String> contestJids) {
                                 .build()));
     }
 
-    private Contest getContestByJidUncached(String contestJid) {
-        return contestDao.selectByJid(contestJid).map(ContestStore::fromModel).orElse(null);
-    }
-
     public Optional<Contest> getContestBySlug(String contestSlug) {
-        return Optional.ofNullable(contestBySlugCache.get(contestSlug));
-    }
-
-    private Contest getContestBySlugUncached(String contestSlug) {
-        return contestDao.selectBySlug(contestSlug).map(ContestStore::fromModel).orElse(null);
+        return contestDao.selectBySlug(contestSlug).map(ContestStore::fromModel);
     }
 
     public Map<String, String> translateSlugsToJids(Set<String> slugs) {
@@ -205,14 +182,6 @@ public Optional<Contest> updateContest(String contestJid, ContestUpdateData cont
                 }
             }
 
-            contestByJidCache.invalidate(contestJid);
-            if (model.slug != null) {
-                contestBySlugCache.invalidate(model.slug);
-            }
-            if (contestUpdateData.getSlug().isPresent()) {
-                contestBySlugCache.invalidate(contestUpdateData.getSlug().get());
-            }
-
             contestUpdateData.getSlug().ifPresent(slug -> model.slug = slug);
             contestUpdateData.getName().ifPresent(name -> model.name = name);
             contestUpdateData.getStyle().ifPresent(style -> model.style = style.name());
@@ -251,8 +220,6 @@ public String importDump(ContestDump dump) {
         model.description = dump.getDescription();
         contestDao.setModelMetadataFromDump(model, dump);
         model = contestDao.persist(model);
-        contestByJidCache.invalidate(model.jid);
-        contestBySlugCache.invalidate(model.slug);
 
         String contestJid = model.jid;
         moduleStore.importStyleDump(contestJid, dump.getStyle());