ci: add checks to determine if build is required (#112)

also save build info upon successful build

.circleci/config.yml

@@ -12,10 +12,8 @@ jobs:
           name: Update Config.mk
           command:  |
             export MY_WORKING_DIRECTORY=`pwd`
-            ls -la
             sed -i "s/NoCall/${CIRCLE_BUILD_NUM}/g" ${MY_WORKING_DIRECTORY}/config.mk
             cat ${MY_WORKING_DIRECTORY}/config.mk
-            set
       - run:
           name: Build
           command: make
@@ -29,6 +27,21 @@ jobs:
           name: Deploy Files
           command: scp -o StrictHostKeyChecking=no ~/${CIRCLE_BRANCH}_${ARTIFACTS_FILE} ${SSH_USER}@${SSH_HOST}:~/
 
+  needs_to_be_built:
+    machine:
+      enabled: true
+    steps:
+      - run:
+          name: Retrieve last build info and check
+          command: ssh ${SSH_USER}@${SSH_HOST} "sh -c ' ~/needs2build.sh ${CIRCLE_PROJECT_USERNAME} ${CIRCLE_PROJECT_REPONAME} ${CIRCLE_BRANCH} ${CIRCLE_SHA1}'"
+  save_build_info:
+      machine:
+        enabled: true
+      steps:
+        - run:
+            name: Save last build info
+            command: ssh ${SSH_USER}@${SSH_HOST} "sh -c ' echo ${CIRCLE_SHA1} > ~/build_info/${CIRCLE_PROJECT_USERNAME}_${CIRCLE_PROJECT_REPONAME}_${CIRCLE_BRANCH}'"
+
   ######################################
   # Nightly
   ######################################
@@ -39,9 +52,6 @@ jobs:
       - run:
           name: Untar Files
           command: ssh ${SSH_USER}@${SSH_HOST} "sh -c 'tar -xjf ~/${CIRCLE_BRANCH}_${ARTIFACTS_FILE} -C ~/'"
-      #- run:
-      #    name: Remove tarball
-      #    command: ssh ${SSH_USER}@${SSH_HOST} "sh -c 'rm ~/${CIRCLE_BRANCH}_${ARTIFACTS_FILE}'"
       - run:
           name: Empty nightly dir
           command: ssh ${SSH_USER}@${SSH_HOST} "sh -c 'rm -rf ${NIGHTLY_DIR}'"
@@ -91,6 +101,11 @@ workflows:
             branches:
               only: develop
     jobs:
+      - build:
+          requires:
+            - needs_to_be_built
+      - save_build_info:
+          requires:
             - build
       - process_artifacts_nightly:
           requires: