From f85e1ab8fc2bb836a6da334f4ffe70bc3f93f99c Mon Sep 17 00:00:00 2001
From: Ryan Liptak <squeek502@hotmail.com>
Date: Tue, 12 Mar 2019 18:20:46 -0700
Subject: [PATCH] Save snapshots as tags so they don't get deleted by git gc

Creates a new tag for each snapshot hash at `refs/snapshots/<author>/<name>/v<version>` with the tag name `snapshots/<author>/<name>/v<version>`. The tag ref is created outside of `refs/tags` so that other methods that iterate the refs don't include snapshots in their iterations (i.e. db.authors() simply returns all nodes in `refs/tags`). It's confirmed that the tag being in `refs/snapshots` still makes it exempt from `git gc`: without the tag, `git gc --prune=all` prunes the snapshot hash, but with the tag it remains after `git gc --prune=all`.

Note: This is an incomplete implementation; it only creates the snapshot tag in `lit add`, not on the server during `lit publish` (or any other places where it might also need to be created)
---
 libs/core.lua | 25 +++++++++++++++++++++++--
 libs/db.lua   | 14 +++++++++-----
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/libs/core.lua b/libs/core.lua
index 3f496df7..ae0a6762 100644
--- a/libs/core.lua
+++ b/libs/core.lua
@@ -156,7 +156,7 @@ local function makeCore(config)
     local encoded = encoders.tag({
       object = hash,
       type = kind,
-      tag = author .. '/' .. name .. "/v" .. version,
+      tag = fullTag,
       tagger = {
         name = config.name,
         email = config.email,
@@ -170,6 +170,27 @@ local function makeCore(config)
     local tagHash = db.saveAs("tag", encoded)
     db.write(author, name, version, tagHash)
     log("new tag", fullTag, "success")
+
+    if meta.snapshot then
+      local snapshotEncoded = encoders.tag({
+        object = meta.snapshot,
+        type = kind,
+        tag = "snapshots/" .. fullTag,
+        tagger = {
+          name = config.name,
+          email = config.email,
+          date = getdate()
+        },
+        message = ""
+      })
+      if key then
+        snapshotEncoded = sshRsa.sign(snapshotEncoded, key)
+      end
+      local snapshotTagHash = db.saveAs("tag", snapshotEncoded)
+      db.write(author, name, version, snapshotTagHash, true)
+      log("new snapshot", 'snapshots/' .. fullTag, "success")
+    end
+
     return author, name, version, tagHash
   end
 
@@ -330,7 +351,7 @@ local function makeCore(config)
         if fingerprints[fingerprint] then
           fingerprints[fingerprint]= nil
         else
-          log("revoking key", username .. ' ' .. fingerprint, "error")
+          log("revoking key", username .. ' ' .. fingerprint, "failure")
           db.revokeKey(username, fingerprint)
         end
       end
diff --git a/libs/db.lua b/libs/db.lua
index 3a0554fd..8855da1d 100644
--- a/libs/db.lua
+++ b/libs/db.lua
@@ -78,16 +78,20 @@ return function (rootPath)
     return match, assert(db.read(author, name, match))
   end
 
-  function db.read(author, name, version)
+  function db.tagRef(author, name, version, isSnapshot)
     version = normalize(version)
-    local ref = string.format("refs/tags/%s/%s/v%s", author, name, version)
+    local refDir = isSnapshot and "snapshots" or "tags"
+    return string.format("refs/%s/%s/%s/v%s", refDir, author, name, version)
+  end
+
+  function db.read(author, name, version, isSnapshot)
+    local ref = db.tagRef(author, name, version, isSnapshot)
     return db.getRef(ref)
   end
 
-  function db.write(author, name, version, hash)
-    version = normalize(version)
+  function db.write(author, name, version, hash, isSnapshot)
     assertHash(hash)
-    local ref = string.format("refs/tags/%s/%s/v%s", author, name, version)
+    local ref = db.tagRef(author, name, version, isSnapshot)
     storage.write(ref, hash .. "\n")
   end