Clean up / optimize makefile, sandbox builds better. (#474)

- Removed a bunch of cruft from overly-generic makefile copypasta
  (many of it doesn't do anything here, and makes it harder to read).
- Corrected a number of dependency chains.  Let me know if I missed
  something!  I've tried to be thorough, but it's hard to be sure.
  in any case, now it shouldn't re-do work unless it's necessary, and
  it can even init in parallel (`make -j4`) from a fresh clone without
  any problems I've seen.
- I was unable to trick Glide into including the necessary packages / versions
  to reliably build things out of vendor... so now there's a `versioned_go_build.sh`
  script to do that.  It'll also warn you if there's a newer version of tool X
  available.
  - Dep can do this pretty easily, add the target command to `require`... though
    I'm not sure what that implies for users-of-this-lib.  Can investigate later.
  - If you change the version vars, it'll automatically build the new version and
    rerun as needed.  And they're not removed with `make clean`, which helps
    keep you from needing to be online to build tools.
- Last but not least: `go test ./...` is equivalent to (or better than)
  testing each package separately, and is often *much* faster because it
  doesn't spend time rebuilding everything.  And now that we're on Go 1.10, it can
  do coverage across all packages too!

---

Before all changes:
```
$ make clean
rm -rf cadence-client
rm -Rf ./build
rm -f dummy

$ time make
rm -rf .gen
go get './vendor/go.uber.org/thriftrw'
go get './vendor/go.uber.org/yarpc/encoding/thrift/thriftrw-plugin-yarpc'
thriftrw --plugin=yarpc --pkg-prefix=go.uber.org/cadence/.gen/go/ --out=.gen/go idl/github.com/uber/cadence/cadence.thrift
thriftrw --plugin=yarpc --pkg-prefix=go.uber.org/cadence/.gen/go/ --out=.gen/go idl/github.com/uber/cadence/shared.thrift
go run ./internal/cmd/tools/copyright/licensegen.go --verifyOnly
go build -i -o dummy internal/cmd/dummy/dummy.go
ok  	go.uber.org/cadence/internal	4.175s	coverage: 66.6% of statements
ok  	go.uber.org/cadence/internal/common/backoff	1.046s	coverage: 93.2% of statements
ok  	go.uber.org/cadence/internal/common/cache	1.462s	coverage: 73.1% of statements
ok  	go.uber.org/cadence/internal/common/metrics	1.055s	coverage: 85.0% of statements
ok  	go.uber.org/cadence/internal/common/util	1.024s	coverage: 5.2% of statements
ok  	go.uber.org/cadence/mocks	1.037s	coverage: 6.7% of statements

real	0m20.177s
user	0m11.994s
sys	0m5.099s

$ time make
rm -rf .gen
go get './vendor/go.uber.org/thriftrw'
go get './vendor/go.uber.org/yarpc/encoding/thrift/thriftrw-plugin-yarpc'
thriftrw --plugin=yarpc --pkg-prefix=go.uber.org/cadence/.gen/go/ --out=.gen/go idl/github.com/uber/cadence/cadence.thrift
thriftrw --plugin=yarpc --pkg-prefix=go.uber.org/cadence/.gen/go/ --out=.gen/go idl/github.com/uber/cadence/shared.thrift
go run ./internal/cmd/tools/copyright/licensegen.go --verifyOnly
ok  	go.uber.org/cadence/internal	4.177s	coverage: 66.8% of statements
ok  	go.uber.org/cadence/internal/common/backoff	1.046s	coverage: 93.2% of statements
ok  	go.uber.org/cadence/internal/common/cache	1.460s	coverage: 73.1% of statements
ok  	go.uber.org/cadence/internal/common/metrics	1.051s	coverage: 85.0% of statements
ok  	go.uber.org/cadence/internal/common/util	1.027s	coverage: 5.2% of statements
ok  	go.uber.org/cadence/mocks	1.038s	coverage: 6.7% of statements

real	0m18.736s
user	0m10.713s
sys	0m4.605s
```

After all changes:
```
$ make clean
rm -Rf .build
rm -Rf .gen

$ time make
./versioned_go_build.sh go.uber.org/thriftrw v1.11.0 .build/thriftrw
./versioned_go_build.sh go.uber.org/yarpc v1.29.1 encoding/thrift/thriftrw-plugin-yarpc .build/thriftrw-plugin-yarpc
	go.uber.org/yarpc has a newer tag: v1.30.0
thriftrw: idl/github.com/uber/cadence/cadence.thrift
go run ./internal/cmd/tools/copyright/licensegen.go --verifyOnly
touch .build/copyright
go build -i -o .build/dummy internal/cmd/dummy/dummy.go
go test ./... -coverprofile=.build/cover.out -race
?   	go.uber.org/cadence	[no test files]
?   	go.uber.org/cadence/activity	[no test files]
?   	go.uber.org/cadence/client	[no test files]
?   	go.uber.org/cadence/encoded	[no test files]
ok  	go.uber.org/cadence/internal	4.188s	coverage: 66.8% of statements
?   	go.uber.org/cadence/internal/cmd/dummy	[no test files]
?   	go.uber.org/cadence/internal/cmd/tools/copyright	[no test files]
?   	go.uber.org/cadence/internal/common	[no test files]
ok  	go.uber.org/cadence/internal/common/backoff	1.060s	coverage: 93.2% of statements
ok  	go.uber.org/cadence/internal/common/cache	1.490s	coverage: 73.1% of statements
ok  	go.uber.org/cadence/internal/common/metrics	1.065s	coverage: 85.0% of statements
ok  	go.uber.org/cadence/internal/common/util	1.037s	coverage: 5.2% of statements
ok  	go.uber.org/cadence/mocks	1.048s	coverage: 6.7% of statements
?   	go.uber.org/cadence/testsuite	[no test files]
?   	go.uber.org/cadence/worker	[no test files]
?   	go.uber.org/cadence/workflow	[no test files]

real	0m34.329s
user	0m25.309s
sys	0m18.131s

$ time make
go test ./... -coverprofile=.build/cover.out -race
?   	go.uber.org/cadence	[no test files]
?   	go.uber.org/cadence/activity	[no test files]
?   	go.uber.org/cadence/client	[no test files]
?   	go.uber.org/cadence/encoded	[no test files]
ok  	go.uber.org/cadence/internal	4.175s	coverage: 66.8% of statements
?   	go.uber.org/cadence/internal/cmd/dummy	[no test files]
?   	go.uber.org/cadence/internal/cmd/tools/copyright	[no test files]
?   	go.uber.org/cadence/internal/common	[no test files]
ok  	go.uber.org/cadence/internal/common/backoff	1.062s	coverage: 93.2% of statements
ok  	go.uber.org/cadence/internal/common/cache	1.500s	coverage: 73.1% of statements
ok  	go.uber.org/cadence/internal/common/metrics	1.060s	coverage: 85.0% of statements
ok  	go.uber.org/cadence/internal/common/util	1.034s	coverage: 5.2% of statements
ok  	go.uber.org/cadence/mocks	1.042s	coverage: 6.7% of statements
?   	go.uber.org/cadence/testsuite	[no test files]
?   	go.uber.org/cadence/worker	[no test files]
?   	go.uber.org/cadence/workflow	[no test files]

real	0m6.635s
user	0m8.372s
sys	0m2.819s
```

So the net effect is a slightly slower initial build, and a much faster second+ build.
Seems worth it :)

.gitignore

@@ -14,3 +14,5 @@ bins
 test
 test.log
 /dummy
+.build
+.bins

Makefile

@@ -1,112 +1,115 @@
 .PHONY: test bins clean cover cover_ci
-PROJECT_ROOT = go.uber.org/cadence
-
-export PATH := $(GOPATH)/bin:$(PATH)
-
-THRIFT_GENDIR=.gen
 
 # default target
 default: test
 
-# define the list of thrift files the service depends on
-# (if you have some)
-THRIFTRW_SRCS = \
-  idl/github.com/uber/cadence/cadence.thrift \
-  idl/github.com/uber/cadence/shared.thrift \
+IMPORT_ROOT := go.uber.org/cadence
+THRIFT_GENDIR := .gen/go
+THRIFTRW_SRC := idl/github.com/uber/cadence/cadence.thrift
+# one or more thriftrw-generated file(s), to create / depend on generated code
+THRIFTRW_OUT := $(THRIFT_GENDIR)/cadence/idl.go
+TEST_ARG ?= -coverprofile=$(BUILD)/cover.out -race
 
-PROGS = cadence-client
-TEST_ARG ?= -race -v -timeout 5m
-BUILD := ./build
+# general build-product folder, cleaned as part of `make clean`
+BUILD := .build
+# general bins folder.  NOT cleaned via `make clean`
+BINS := .bins
 
-THRIFT_GEN=$(GOPATH)/bin/thrift-gen
+# Automatically gather all srcs + a "sentinel" thriftrw output file (which forces generation).
+ALL_SRC := $(THRIFTRW_OUT) $(shell \
+	find . -name "*.go" | \
+	grep -v \
+	-e vendor/ \
+	-e .gen/ \
+	-e .build/ \
+)
 
-define thriftrwrule
-THRIFTRW_GEN_SRC += $(THRIFT_GENDIR)/go/$1/$1.go
-
-$(THRIFT_GENDIR)/go/$1/$1.go:: $2
-	@mkdir -p $(THRIFT_GENDIR)/go
-	$(ECHO_V)thriftrw --plugin=yarpc --pkg-prefix=$(PROJECT_ROOT)/$(THRIFT_GENDIR)/go/ --out=$(THRIFT_GENDIR)/go $2
-endef
+# Files that needs to run lint.  excludes testify mocks and the thrift sentinel.
+LINT_SRC := $(filter-out ./mock% $(THRIFTRW_OUT),$(ALL_SRC))
 
-$(foreach tsrc,$(THRIFTRW_SRCS),$(eval $(call \
-	thriftrwrule,$(basename $(notdir \
-	$(shell echo $(tsrc) | tr A-Z a-z))),$(tsrc))))
+THRIFTRW_VERSION := v1.11.0
+YARPC_VERSION := v1.29.1
+GOLINT_VERSION := 470b6b0bb3005eda157f0275e2e4895055396a81
 
-# Automatically gather all srcs
-ALL_SRC := $(shell find . -name "*.go" | grep -v -e Godeps -e vendor \
-	-e ".*/\..*" \
-	-e ".*/_.*")
+# versioned tools.  just change the version vars above, it'll automatically trigger a rebuild.
+$(BINS)/versions/thriftrw-$(THRIFTRW_VERSION):
+	./versioned_go_build.sh go.uber.org/thriftrw $(THRIFTRW_VERSION) $@
 
-# Files that needs to run lint, exclude testify mock from lint
-LINT_SRC := $(filter-out ./mock%,$(ALL_SRC))
+$(BINS)/versions/yarpc-$(YARPC_VERSION):
+	./versioned_go_build.sh go.uber.org/yarpc $(YARPC_VERSION) encoding/thrift/thriftrw-plugin-yarpc $@
 
-# all directories with *_test.go files in them
-TEST_DIRS := $(sort $(dir $(filter %_test.go,$(ALL_SRC))))
+$(BINS)/versions/golint-$(GOLINT_VERSION):
+	./versioned_go_build.sh golang.org/x/lint $(GOLINT_VERSION) golint $@
 
-vendor:
-	glide install
+# stable tool targets.  depend on / execute these instead of the versioned ones.
+# this versioned-to-nice-name thing is mostly because thriftrw depends on the yarpc
+# bin to be named "thriftrw-plugin-yarpc".
+$(BINS)/thriftrw: $(BINS)/versions/thriftrw-$(THRIFTRW_VERSION)
+	@ln -fs $(CURDIR)/$< $@
 
-yarpc-install: vendor
-	go get './vendor/go.uber.org/thriftrw'
-	go get './vendor/go.uber.org/yarpc/encoding/thrift/thriftrw-plugin-yarpc'
+$(BINS)/thriftrw-plugin-yarpc: $(BINS)/versions/yarpc-$(YARPC_VERSION)
+	@ln -fs $(CURDIR)/$< $@
 
-clean_thrift:
-	rm -rf .gen
+$(BINS)/golint: $(BINS)/versions/golint-$(GOLINT_VERSION)
+	@ln -fs $(CURDIR)/$< $@
 
-thriftc: clean_thrift yarpc-install $(THRIFTRW_GEN_SRC)
+vendor: vendor/glide.updated
 
-copyright: ./internal/cmd/tools/copyright/licensegen.go
-	go run ./internal/cmd/tools/copyright/licensegen.go --verifyOnly
-
-vendor/glide.updated: glide.lock glide.yaml
+vendor/glide.updated: glide.lock
 	glide install
 	touch vendor/glide.updated
 
-dummy: vendor/glide.updated $(ALL_SRC)
-	go build -i -o dummy internal/cmd/dummy/dummy.go
-
-test: bins
-	@rm -f test
-	@rm -f test.log
-	@for dir in $(TEST_DIRS); do \
-		go test -race -coverprofile=$@ "$$dir" | tee -a test.log; \
-	done;
+$(THRIFTRW_OUT): $(THRIFTRW_SRC) $(BINS)/thriftrw $(BINS)/thriftrw-plugin-yarpc
+	@echo 'thriftrw: $(THRIFTRW_SRC)'
+	@mkdir -p $(dir $@)
+	@# needs to be able to find the thriftrw-plugin-yarpc bin in PATH
+	@PATH="$(BINS)" \
+		$(BINS)/thriftrw \
+		--plugin=yarpc \
+		--pkg-prefix=$(IMPORT_ROOT)/$(THRIFT_GENDIR) \
+		--out=$(THRIFT_GENDIR) \
+		$(THRIFTRW_SRC)
 
-bins: thriftc copyright lint dummy
+clean_thrift:
+	rm -rf .gen
 
-cover_profile: clean copyright lint vendor/glide.updated
+# `make copyright` or depend on "copyright" to force-run licensegen,
+# or depend on $(BUILD)/copyright to let it run as needed.
+copyright $(BUILD)/copyright: $(ALL_SRC)
 	@mkdir -p $(BUILD)
-	@echo "mode: atomic" > $(BUILD)/cover.out
+	go run ./internal/cmd/tools/copyright/licensegen.go --verifyOnly
+	@touch $(BUILD)/copyright
+
+$(BUILD)/dummy: vendor/glide.updated $(ALL_SRC)
+	go build -i -o $@ internal/cmd/dummy/dummy.go
+
+test $(BUILD)/cover.out: $(BUILD)/copyright $(BUILD)/dummy $(ALL_SRC)
+	go test ./... $(TEST_ARG)
 
-	@echo Testing packages:
-	@for dir in $(TEST_DIRS); do \
-		mkdir -p $(BUILD)/"$$dir"; \
-		go test "$$dir" $(TEST_ARG) -coverprofile=$(BUILD)/"$$dir"/coverage.out || exit 1; \
-		cat $(BUILD)/"$$dir"/coverage.out | grep -v "mode: atomic" >> $(BUILD)/cover.out; \
-	done;
+bins: $(ALL_SRC) $(BUILD)/copyright lint $(BUILD)/dummy
 
-cover: cover_profile
+cover: $(BUILD)/cover.out
 	go tool cover -html=$(BUILD)/cover.out;
 
-cover_ci: cover_profile
+cover_ci: $(BUILD)/cover.out
 	goveralls -coverprofile=$(BUILD)/cover.out -service=travis-ci || echo -e "\x1b[31mCoveralls failed\x1b[m";
 
 # golint fails to report many lint failures if it is only given a single file
-# to work on at a time.  and we can't exclude files from its checks, so for
-# best results we need to give it a whitelist of every file in every package
-# that we want linted.
+# to work on at a time, and it can't handle multiple packages at once, *and*
+# we can't exclude files from its checks, so for best results we need to give
+# it a whitelist of every file in every package that we want linted, per package.
 #
 # so lint + this golint func works like:
-# - iterate over all dirs (outputs "./folder/")
+# - iterate over all lintable dirs (outputs "./folder/")
 # - find .go files in a dir (via wildcard, so not recursively)
 # - filter to only files in LINT_SRC
 # - if it's not empty, run golint against the list
 define lint_if_present
-test -n "$1" && golint -set_exit_status $1
+test -n "$1" && $(BINS)/golint -set_exit_status $1
 endef
 
-lint:
-	@$(foreach pkg,\
+lint: $(BINS)/golint $(ALL_SRC)
+	$(foreach pkg,\
 		$(sort $(dir $(LINT_SRC))), \
 		$(call lint_if_present,$(filter $(wildcard $(pkg)*.go),$(LINT_SRC))) || ERR=1; \
 	) test -z "$$ERR" || exit 1
@@ -121,6 +124,5 @@ fmt:
 	@gofmt -w $(ALL_SRC)
 
 clean:
-	rm -rf cadence-client
 	rm -Rf $(BUILD)
-	rm -f dummy
+	rm -Rf .gen

versioned_go_build.sh

@@ -0,0 +1,172 @@
+#!/bin/bash
+
+set -euf -o pipefail
+
+# In a nutshell, this script:
+# - makes a tempdir and moves to it
+# - go gets the requested bin (but does not install it)
+# - cds to the repo
+# - checks out the requested version
+# - maybe runs `glide install`
+# - builds the bin and puts it where you told it to.
+#
+# Since doing that verbatim is a bit noisy, and pinning tools tends to
+# cause them to slowly get out of date, it does two additional things:
+# - suppresses output unless `--debug` is passed
+# - checks for newer commits / tags than the one you passed, and
+#   prints the newer sha/version (if any) to stderr so it's always visible.
+
+usage () {
+    echo 'Installs a specific version of a go-gettable bin to the specified location.'
+    echo ''
+    echo 'Usage:'
+    echo ''
+    echo -e "\\t$0 [--debug] go-gettable-repo version [path-to-bin-in-repo] install-location"
+    echo ''
+    echo 'Examples:'
+    echo ''
+    echo -e "\\t$0 go.uber.org/thriftrw 1.10.0 somewhere/thriftrw"
+    echo -e '\t\tInstalls v1.10.0 of go.uber.org/thriftrw to somewhere/thriftrw.'
+    echo -e '\t\tNotice that go.uber.org/thriftrw is both the repository AND the binary name.'
+    echo ''
+    echo -e "\\t$0 golang.org/x/lint SOME_SHA golint somewhere/golint"
+    echo -e '\t\tInstalls a specific SHA of e.g. "golang.org/x/lint/golint" to "somewhere/golint",'
+    echo -e '\t\tNotice that the golint bin is in a subfolder of the golang.org/x/lint repository.'
+
+    exit 1
+}
+
+num_commits_behind () {
+    head=$1
+    git rev-list "..$head" | wc -l | tr -dc '0-9'
+}
+
+is_versioned () {
+    # returns truthy if the arg is version-like.
+
+    str=$1
+    if echo "$str" | grep -q -E "$VERSION_TAG_REGEX"; then
+        return 0
+    fi
+    return 1
+}
+
+most_recent_version_tag () {
+    # using xargs because it's safer (for big lists) + it doesn't result in
+    # a ton of SHAs in debug output like `git describe --tags $(...)` causes.
+    #
+    # in brief:
+    # - get all tagged shas
+    # - get their tags
+    # - grep for version-like tags
+    # - sort by version
+    # - return the "biggest"
+
+    git rev-list --tags \
+    | xargs git describe --always --tags 2>/dev/null \
+    | grep -E "$VERSION_TAG_REGEX" \
+    | sort -Vr \
+    | head -n 1
+}
+
+# matches "v1[.2[.3[.4]]]" exactly or fails.
+# this intentionally does not match "v1.2.3-ae83c2" tags, nor "v1.2-pre", etc,
+# as these are not likely "real" release versions.
+declare -r VERSION_TAG_REGEX='^v?\d+(\.\d+){0,3}$'
+
+# output control vars
+declare DEBUG=
+declare TO_DEV_NULL=
+declare QUIET=
+
+# build control vars
+declare -x GOPATH
+declare GO_GETTABLE_REPO
+declare VERSION
+declare GO_GETTABLE_BIN
+declare INSTALL_LOCATION
+
+# handle optional debug (and consume the arg)
+if [ "$1" == "--debug" ]; then
+    shift  # consume it
+    DEBUG=1
+else
+    # otherwise, redirect to /dev/null (requires eval)
+    TO_DEV_NULL='>/dev/null'
+    # pass quiet flags where needed (do not quote)
+    QUIET='--quiet'
+fi
+
+# must have 3 or 4 args
+[ $# -ge 3 ] || usage
+[ $# -le 4 ] || usage
+
+[ -z $DEBUG ] || set -x
+
+#
+# Set up some variables / the temp folder
+#
+
+# set up gopath, and make sure it's cleaned up regardless of how we exit
+GOPATH=$(mktemp -d)
+trap 'rm -rf $GOPATH' EXIT
+
+GO_GETTABLE_REPO="$1"
+VERSION="$2"
+if [ $# -eq 4 ]; then
+    # bin resides in a sub-folder
+    GO_GETTABLE_BIN="$1/$3"
+    INSTALL_LOCATION="$4"
+elif [ $# -eq 3 ]; then
+    # repo == bin
+    GO_GETTABLE_BIN="$1"
+    INSTALL_LOCATION="$3"
+else
+    # should be unreachable
+    usage
+fi
+
+#
+# Pull the repo, set to the correct version
+#
+
+go get -d "$GO_GETTABLE_BIN"
+# eval so redirection works when quiet
+eval "pushd $GOPATH/src/$GO_GETTABLE_REPO $TO_DEV_NULL"
+
+# save for the version check
+HEAD="$(git rev-parse HEAD)"
+
+# silently check out, reduces a lot of default spam
+git checkout $QUIET "$VERSION"
+
+#
+# Check if we're building an old version, warn if so
+#
+
+if is_versioned "$VERSION"; then
+    # versioned, check for newer tags.
+    LATEST="$(most_recent_version_tag)"
+    # use sort to check if VERSION >= LATEST, or warn about the newer version
+    echo -e "$VERSION\\n$LATEST" | sort -Vrc 2>/dev/null || (>&2 echo -e "\\t$GO_GETTABLE_REPO has a newer tag: $LATEST")
+else
+    # not versioned, check for newer commits
+    BEHIND="$(num_commits_behind "$HEAD")"
+    # should be zero, or warn about the newer version
+    [ "$BEHIND" -eq 0 ] || (>&2 echo -e "\\t$GO_GETTABLE_REPO is $BEHIND commits behind the current HEAD: $HEAD")
+fi
+
+#
+# Build the bin, install to the correct location
+#
+
+# only glide install when there is a glide file, or it tries to install
+# to the current repo (not in our current folder)
+if [ -f glide.lock ]; then
+    glide $QUIET install
+fi
+
+# eval so redirection works when quiet
+eval "popd $TO_DEV_NULL"
+
+go build -o "$INSTALL_LOCATION" "$GO_GETTABLE_BIN"