dev: only support watchman (#12252)

Maintaining three different ways to watch files leads to unneccessary
bugs. Instead lets pick just one.

dev/changewatch.sh

@@ -1,73 +1,17 @@
 #!/usr/bin/env bash
 
+set -e
+unset CDPATH
 cd "$(dirname "${BASH_SOURCE[0]}")/.." # cd to repo root dir
-GO_DIRS="$(./dev/watchdirs.sh) ${WATCH_ADDITIONAL_GO_DIRS}"
 
-dirs_starstar() {
-  for i; do echo "'$i/**/*.go'"; done
-}
+# Wrapper for watchman. To debug which changes it detect set the environment
+# variable WATCHMAN_DEBUG=t
 
-dirs_path() {
-  for i; do echo "-path $i"; done
-}
+if [ ! -x "$(command -v watchman)" ]; then
+  echo "Please install watchman. https://facebook.github.io/watchman/docs/install.html"
+  echo
+  echo "  brew install watchman"
+  exit 1
+fi
 
-useChokidar() {
-  echo >&2 "Using chokidar."
-  # eval so the expansion can produce quoted things, and eval can eat the
-  # quotes, so it doesn't try to expand wildcards.
-  # shellcheck disable=2046,2086
-  eval exec chokidar --silent \
-    $(dirs_starstar $GO_DIRS) \
-    cmd/frontend/graphqlbackend/schema.graphql \
-    "'schema/*.json'" \
-    "'docker-images/grafana/jsonnet/*.jsonnet'" \
-    "'monitoring/*'" \
-    "'cmd/symbols/**/*'" \
-    "'cmd/symbols/.ctags.d/*'" \
-    -c "'./dev/handle-change.sh {path}'"
-}
-
-execInotifywrapper() {
-  echo >&2 "Using inotifywrapper."
-  set -e
-  pushd dev/inotifywrapper
-  go build
-  popd
-  # shellcheck disable=2046,2086
-  exec dev/inotifywrapper/inotifywrapper $(dirs_path $GO_DIRS) \
-    -match '\.go$' \
-    -match 'cmd/frontend/graphqlbackend/schema\.graphql' \
-    -match 'schema/.*.json' \
-    -match 'docker-images/grafana/jsonnet/*.jsonnet' \
-    -match 'monitoring/*' \
-    -cmd './dev/handle-change.sh'
-}
-
-execWatchman() {
-  echo >&2 "Using watchman."
-  set -e
-  pushd dev/watchmanwrapper
-  go build
-  popd
-  exec dev/watchmanwrapper/watchmanwrapper dev/handle-change.sh <<-EOT
-["subscribe", ".", "gochangewatch", {
-  "expression": ["allof",
-    ["not", ["anyof",
-      ["match", ".*"],
-      ["suffix", "_test.go"]]],
-    ["anyof",
-      ["suffix", "go"],
-      ["dirname", "cmd/symbols"],
-      ["dirname", "schema"],
-      ["dirname", "docker-images/grafana/jsonnet"],
-      ["dirname", "monitoring"],
-      ["name", "cmd/frontend/graphqlbackend/schema.graphql", "wholename"]]],
-  "fields": ["name"]
-}]
-EOT
-}
-
-[ -x "$(command -v watchman)" ] && execWatchman
-[ -x "$(command -v inotifywait)" ] && execInotifywrapper
-
-useChokidar
+exec go run ./dev/watchmanwrapper dev/handle-change.sh <dev/watchmanwrapper/watch.json

dev/watchmanwrapper/watch.json

@@ -0,0 +1,21 @@
+[
+  "subscribe",
+  ".",
+  "gochangewatch",
+  {
+    "expression": [
+      "allof",
+      ["not", ["anyof", ["match", ".*"], ["suffix", "_test.go"]]],
+      [
+        "anyof",
+        ["suffix", "go"],
+        ["dirname", "cmd/symbols"],
+        ["dirname", "schema"],
+        ["dirname", "docker-images/grafana/jsonnet"],
+        ["dirname", "monitoring"],
+        ["name", "cmd/frontend/graphqlbackend/schema.graphql", "wholename"]
+      ]
+    ],
+    "fields": ["name"]
+  }
+]

doc/dev/local_development.md

@@ -76,6 +76,7 @@ Sourcegraph has the following dependencies:
 - [SQLite](https://www.sqlite.org/index.html) tools
 - [Golang Migrate](https://github.com/golang-migrate/migrate/) (v4.7.0 or higher)
 - [Comby](https://github.com/comby-tools/comby/) (v0.11.3 or higher)
+- [Watchman](https://facebook.github.io/watchman/)
 
 The following are two recommendations for installing these dependencies:
 
@@ -93,7 +94,7 @@ The following are two recommendations for installing these dependencies:
 3.  Install Go, Node Version Manager, PostgreSQL, Redis, Git, NGINX, golang-migrate, Comby, SQLite tools, and jq with the following command:
 
     ```
-    brew install go yarn redis postgresql git gnu-sed nginx golang-migrate comby sqlite pcre FiloSottile/musl-cross/musl-cross jq
+    brew install go yarn redis postgresql git gnu-sed nginx golang-migrate comby sqlite pcre FiloSottile/musl-cross/musl-cross jq watchman
     ```
 
 4.  Install the Node Version Manager (`nvm`) using:
@@ -182,6 +183,9 @@ The following are two recommendations for installing these dependencies:
     # install comby (you must rename the extracted binary to `comby` and move the binary into your $PATH)
     curl -L https://github.com/comby-tools/comby/releases/download/0.11.3/comby-0.11.3-x86_64-linux.tar.gz | tar xvz
 
+    # install watchman (you must put the binary and shared libraries on your $PATH and $LD_LIBRARY_PATH)
+    curl -L https://github.com/facebook/watchman/releases/download/v2020.07.13.00/watchman-v2020.07.13.00-linux.zip
+
     # nvm (to manage Node.js)
     NVM_VERSION="$(curl https://api.github.com/repos/nvm-sh/nvm/releases/latest | jq -r .name)"
     curl -L https://raw.githubusercontent.com/nvm-sh/nvm/"$NVM_VERSION"/install.sh -o install-nvm.sh