From c8cd2cebb7c0ddc8b144ddc062cdc8a81d032a4d Mon Sep 17 00:00:00 2001
From: Jordan Bancino <jordan@bancino.net>
Date: Thu, 15 Dec 2022 02:39:58 +0000
Subject: [PATCH] Implement DbDelete()

---
 TODO.txt                         |  2 +-
 man/man7/telodendria-changelog.7 |  8 +++-
 src/Db.c                         | 70 ++++++++++++++++++++++++++++++++
 src/include/Db.h                 |  3 ++
 4 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/TODO.txt b/TODO.txt
index b2e7b01..ecce73a 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -11,7 +11,7 @@ Key:
 Milestone: v0.1.1
 -----------------
 
-[ ] DbDelete()
+[x] DbDelete()
 [ ] UtilRandomString()
 [ ] Database version file
 [ ] User registration
diff --git a/man/man7/telodendria-changelog.7 b/man/man7/telodendria-changelog.7
index 7eea9bf..cadae6f 100644
--- a/man/man7/telodendria-changelog.7
+++ b/man/man7/telodendria-changelog.7
@@ -1,4 +1,4 @@
-.Dd $Mdocdate: December 14 2022 $
+.Dd $Mdocdate: December 15 2022 $
 .Dt TELODENDRIA-CHANGELOG 7
 .Os Telodendria Project
 .Sh NAME
@@ -37,6 +37,12 @@ Changes:
 .It
 Improved HTTP request logging by removing unnecessary
 log entries and making errors more specific.
+.It
+Added a way to safely delete objects from the database.
+While the database is for persistent storage, there may
+be some ephemeral data that lives there only for a short
+while, so it will be necessary to remove that data when
+necessary.
 .El
 .Pp
 Bug fixes:
diff --git a/src/Db.c b/src/Db.c
index 045b630..88c9a83 100644
--- a/src/Db.c
+++ b/src/Db.c
@@ -537,6 +537,76 @@ DbCreate(Db * db, size_t nArgs,...)
     return DbLockFromArr(db, args);
 }
 
+int
+DbDelete(Db * db, size_t nArgs,...)
+{
+    va_list ap;
+    Array *args;
+    char *file;
+    char *hash;
+    int ret = 1;
+    DbRef *ref;
+
+    if (!db)
+    {
+        return 0;
+    }
+
+    va_start(ap, nArgs);
+    args = ArrayFromVarArgs(nArgs, ap);
+    va_end(ap);
+
+    pthread_mutex_lock(&db->lock);
+
+    hash = DbHashKey(args);
+    file = DbFileName(db, args);
+
+    ref = HashMapGet(db->cache, hash);
+    if (ref)
+    {
+        pthread_mutex_lock(&ref->lock);
+
+        HashMapDelete(db->cache, hash);
+        JsonFree(ref->json);
+        ArrayFree(ref->name);
+
+        db->cacheSize -= ref->size;
+
+        if (ref->next)
+        {
+            ref->next->prev = ref->prev;
+        }
+        else
+        {
+            db->mostRecent = ref->prev;
+        }
+
+        if (ref->prev)
+        {
+            ref->prev->next = ref->next;
+        }
+        else
+        {
+            db->leastRecent = ref->next;
+        }
+
+        pthread_mutex_unlock(&ref->lock);
+        pthread_mutex_destroy(&ref->lock);
+        Free(ref);
+    }
+
+    Free(hash);
+
+    if (UtilLastModified(file))
+    {
+        ret = remove(file) == 0;
+    }
+
+    pthread_mutex_unlock(&db->lock);
+
+    return ret;
+}
+
 DbRef *
 DbLock(Db * db, size_t nArgs,...)
 {
diff --git a/src/include/Db.h b/src/include/Db.h
index d1f9397..32cd1ab 100644
--- a/src/include/Db.h
+++ b/src/include/Db.h
@@ -44,6 +44,9 @@ extern void
 extern DbRef *
  DbCreate(Db *, size_t,...);
 
+extern int
+ DbDelete(Db *, size_t,...);
+
 extern DbRef *
  DbLock(Db *, size_t,...);