From: Alexandre Terrasa <alexandre@moz-code.org>
Date: Thu, 22 Jan 2015 10:49:05 +0000 (+0100)
Subject: lib/github: implements caching to maximize rate limit.
X-Git-Tag: v0.7.1~17^2
X-Git-Url: http://nitlanguage.org

lib/github: implements caching to maximize rate limit.

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>
---

diff --git a/.gitignore b/.gitignore
index 5cd49a0..2156619 100644
--- a/.gitignore
+++ b/.gitignore
@@ -55,3 +55,4 @@ nitunit.xml
 *.stub.nit.[ch]
 
 .metadata/*
+.github_data
diff --git a/lib/github/api.nit b/lib/github/api.nit
index b979b5d..2655ae3 100644
--- a/lib/github/api.nit
+++ b/lib/github/api.nit
@@ -133,7 +133,7 @@ class GithubAPI
 
 	# Load the json object from Github.
 	# See `GithubEntity::load_from_github`.
-	private fun load_from_github(key: String): JsonObject do
+	protected fun load_from_github(key: String): JsonObject do
 		message(1, "Get {key} (github)")
 		var res = get(key)
 		if was_error then return new JsonObject
diff --git a/lib/github/cache.nit b/lib/github/cache.nit
new file mode 100644
index 0000000..559b4a8
--- /dev/null
+++ b/lib/github/cache.nit
@@ -0,0 +1,80 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Enable caching on Github API accesses.
+#
+# If `GithubAPI::enable_cache` is set to true then Github JSON responses
+# will be cached locally using `JsonStore`.
+#
+# Cache can be used to limit the number of access on the API and lighten
+# the rate limit on your github key.
+#
+# Usage:
+#
+# ~~~
+# var api = new GithubAPI(get_github_oauth)
+# api.enable_cache = true
+#
+# var name = "privat/nit"
+# assert not api.has_cache(name)
+# var repo = api.load_repo(name) # load from GitHub
+# assert api.has_cache(name)
+# repo = api.load_repo(name) # load from cache
+#
+# api.clear_cache
+# assert not api.has_cache(name)
+# ~~~
+module cache
+
+intrude import github::api
+import json::store
+
+redef class GithubAPI
+
+	# Enable caching for this client.
+	# Default is `false`.
+	var enable_cache = false is writable
+
+	# JsonStore used to cache data.
+	#
+	# Default directory is `".github_data/"`.
+	var store = new JsonStore(".github_data/") is writable, lazy
+
+	# Delete the cache directory.
+	fun clear_cache do store.clear
+
+	# If no cache data is found for `key` then json is loaded from Github API.
+	redef fun load_from_github(key) do
+		if not enable_cache then return super
+		if store.has_key(key) then
+			message(1, "Get {key} (cache)")
+			was_error = false
+			return store.load_object(key)
+		end
+		var obj = super
+		if not was_error then cache(key, obj)
+		return obj
+	end
+
+	# Save `json` data in cache under `key`.
+	private fun cache(key: String, json: JsonObject) do
+		message(2, "Cache key {key}")
+		store.store_object(key, json)
+	end
+
+	# Check if a cache file exists for `key`.
+	fun has_cache(key: String): Bool do
+		return store.has_key(key)
+	end
+end
diff --git a/lib/github/github.nit b/lib/github/github.nit
index 778f826..9bc63a8 100644
--- a/lib/github/github.nit
+++ b/lib/github/github.nit
@@ -15,4 +15,4 @@
 # Github API related features.
 module github
 
-import api
+import cache