Cache redis server compilation on CI

Author: byroot

.travis.yml

@@ -1,5 +1,7 @@
 language: ruby
-
+cache:
+    directories:
+      - tmp/cache
 before_install:
   - gem update --system 2.6.14
   - gem --version

bin/build

@@ -0,0 +1,71 @@
+#!/usr/bin/env ruby
+
+TARBALL = ARGV[0]
+
+require 'digest/sha1'
+require 'fileutils'
+
+class Builder
+  def initialize(redis_branch, tmp_dir)
+    @redis_branch = redis_branch
+    @tmp_dir = tmp_dir
+    @build_dir = File.join(@tmp_dir, "cache", "redis-#{redis_branch}")
+  end
+
+  def run
+    download_tarball
+    if old_checkum != checksum
+      build
+      update_checksum
+    end
+    0
+  end
+
+  def download_tarball
+    command!('wget', tarball_url, '-O', tarball_path)
+  end
+
+  def tarball_path
+    File.join(@tmp_dir, "redis-#{@redis_branch}.tar.gz")
+  end
+
+  def tarball_url
+    "https://github.com/antirez/redis/archive/#{@redis_branch}.tar.gz"
+  end
+
+  def build
+    FileUtils.rm_rf(@build_dir)
+    FileUtils.mkdir_p(@build_dir)
+    command!('tar', 'xf', tarball_path, '-C', File.expand_path('../', @build_dir))
+    Dir.chdir(@build_dir) do
+      command!('make')
+    end
+  end
+
+  def update_checksum
+    File.write(checksum_path, checksum)
+  end
+
+  def old_checkum
+    File.read(checksum_path)
+  rescue Errno::ENOENT
+    nil
+  end
+
+  def checksum_path
+    File.join(@build_dir, 'build.checksum')
+  end
+
+  def checksum
+    @checksum ||= Digest::SHA1.file(tarball_path).hexdigest
+  end
+
+  def command!(*args)
+    puts "$ #{args.join(' ')}"
+    unless system(*args)
+      raise "Command failed with status #{$?.exitstatus}"
+    end
+  end
+end
+
+exit Builder.new(ARGV[0], ARGV[1]).run

makefile

@@ -1,7 +1,7 @@
 TEST_FILES   := $(shell find test -name *_test.rb -type f)
 REDIS_BRANCH := unstable
 TMP          := tmp
-BUILD_DIR    := ${TMP}/redis-${REDIS_BRANCH}
+BUILD_DIR    := ${TMP}/cache/redis-${REDIS_BRANCH}
 TARBALL      := ${TMP}/redis-${REDIS_BRANCH}.tar.gz
 BINARY       := ${BUILD_DIR}/src/redis-server
 PID_PATH     := ${BUILD_DIR}/redis.pid
@@ -17,19 +17,14 @@ test: ${TEST_FILES}
 ${TMP}:
 	mkdir $@
 
-${TARBALL}: ${TMP}
-	wget https://github.com/antirez/redis/archive/${REDIS_BRANCH}.tar.gz -O $@
-
-${BINARY}: ${TARBALL} ${TMP}
-	rm -rf ${BUILD_DIR}
-	mkdir -p ${BUILD_DIR}
-	tar xf ${TARBALL} -C ${TMP}
-	cd ${BUILD_DIR} && make
+${BINARY}: ${TMP}
+	bin/build ${REDIS_BRANCH} ${TMP}
 
 stop:
 	(test -f ${PID_PATH} && (kill $$(cat ${PID_PATH}) || true) && rm -f ${PID_PATH}) || true
 
 start: ${BINARY}
+	echo ${BINARY}
 	${BINARY}                     \
 		--daemonize  yes            \
 		--pidfile    ${PID_PATH}    \