Legocastle job to report lite build binary size to scuba

Summary:
Add a legocastle job to continuously build the last 10 commits every 4 hours and report lite build binary size to scuba.
Closes https://github.com/facebook/rocksdb/pull/3511

Differential Revision: D7001730

Pulled By: yiwu-arbug

fbshipit-source-id: 7c8ca87c46d663c786a0d32be69ebbe7b19a5eb9

build_tools/rocksdb-lego-determinator

@@ -352,6 +352,22 @@ LITE_BUILD_COMMANDS="[
     }
 ]"
 
+#
+# Report RocksDB lite binary size to scuba
+REPORT_LITE_BINARY_SIZE_COMMANDS="[
+    {
+        'name':'Rocksdb Lite Binary Size',
+        'oncall':'$ONCALL',
+        'steps': [
+            $CLEANUP_ENV,
+            {
+                'name':'Report RocksDB Lite binary size to scuba',
+                'shell':'tools/report_lite_binary_size.sh',
+                'user':'root',
+            },
+        ],
+]"
+
 #
 # RocksDB stress/crash test
 #
@@ -728,6 +744,9 @@ case $1 in
   lite)
     echo $LITE_BUILD_COMMANDS
     ;;
+  report_lite_binary_size)
+    echo $REPORT_LITE_BINARY_SIZE_COMMANDS
+    ;;
   stress_crash)
     echo $STRESS_CRASH_TEST_COMMANDS
     ;;

tools/report_lite_binary_size.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Script to report lite build binary size for latest RocksDB commits.
+# Usage:
+#   ./report_lite_binary_size [num_recent_commits]
+
+num_recent_commits=${1:-10}
+
+echo "Computing RocksDB lite build binary size for the most recent $num_recent_commits commits."
+
+for ((i=0; i < num_recent_commits; i++))
+do
+  git checkout master~$i
+  commit_hash=$(git show -s --format=%H)
+  commit_time=$(git show -s --format=%ct)
+
+  # It would be nice to check if scuba already have a record for the commit,
+  # but sandcastle don't seems to have scuba CLI installed.
+
+  make clean
+  make OPT=-DROCKSDB_LITE static_lib
+
+  if make OPT=-DROCKSDB_LITE static_lib
+  then
+    build_succeeded='true'
+    strip librocksdb.a
+    binary_size=$(stat -c %s librocksdb.a)
+  else
+    build_succeeded='false'
+    binary_size=0
+  fi
+
+  current_time="\"time\": $(date +%s)"
+  commit_hash="\"hash\": \"$commit_hash\""
+  commit_time="\"commit_time\": $commit_time"
+  build_succeeded="\"build_succeeded\": \"$build_succeeded\""
+  binary_size="\"binary_size\": $binary_size"
+
+  scribe_log="{\"int\":{$current_time, $commit_time, $binary_size}, \"normal\":{$commit_hash, $build_succeeded}}"
+  echo "Logging to scribe: $scribe_log"
+  scribe_cat perfpipe_rocksdb_lite_build "$scribe_log"
+done