build(jemalloc): Install Jemalloc if missing via Makefile. (#6463)

This PR adds a jemalloc target to makefile to install jemalloc. The make install command will install jemalloc if it's not already installed.

The make jemalloc target currently fails on docker with command sudo not found. I don't have a solution for it.

The change doesn't work on macOS or Windows. Dgraph builds with jemalloc by default on Linux only.

Co-authored-by: Daniel Mai <daniel@dgraph.io>

Author: Ibrahim Jarif

dgraph/Makefile

@@ -29,7 +29,11 @@ else
 BUILD_VERSION ?= $(shell git describe --always --tags)
 endif
 
-BUILD_TAGS    ?=
+GOOS          ?= $(shell go env GOOS)
+# Only build with jemalloc on Linux
+ifeq ($(GOOS),linux)
+	BUILD_TAGS ?= jemalloc
+endif
 GOPATH        ?= $(shell go env GOPATH)
 MODIFIED = $(shell git diff-index --quiet HEAD || echo "-mod")
 
@@ -62,10 +66,14 @@ ifneq ($(strip $(BUILD_RACE)),)
 	BUILD_FLAGS += -race
 endif
 
+# jemalloc stuff
+HAS_JEMALLOC = $(shell test -f /usr/local/lib/libjemalloc.a && echo "jemalloc")
+JEMALLOC_URL = "https://github.com/jemalloc/jemalloc/releases/download/5.2.1/jemalloc-5.2.1.tar.bz2"
+
 .PHONY: all $(BIN)
 all: $(BIN)
 
-$(BIN): clean
+$(BIN): clean jemalloc
 	@go build $(BUILD_FLAGS) -o $(BIN)
 
 clean:
@@ -74,8 +82,22 @@ clean:
 uninstall:
 	@go clean -i -x
 
-install:
+install: jemalloc
 	@echo "Commit SHA256: `git rev-parse HEAD`"
 	@echo "Old SHA256:" `sha256sum $(GOPATH)/bin/$(BIN) 2>/dev/null | cut -c-64`
 	@go install $(BUILD_FLAGS)
 	@echo "New SHA256:" `sha256sum $(GOPATH)/bin/$(BIN) 2>/dev/null | cut -c-64`
+
+jemalloc:
+	@if [ -z "$(HAS_JEMALLOC)" ] ; then \
+	    mkdir -p /tmp/jemalloc-temp && cd /tmp/jemalloc-temp ; \
+	    echo "Downloading jemalloc" ; \
+	    curl -s -L ${JEMALLOC_URL} -o jemalloc.tar.bz2 ; \
+	    tar xjf ./jemalloc.tar.bz2 ; \
+	    cd jemalloc-5.2.1 ; \
+	    ./configure --with-jemalloc-prefix='je_' ; \
+	    make ; \
+	    echo "==== Need sudo access to install jemalloc" ; \
+	    sudo make install ; \
+	fi
+