Speed up go generate

Makefile

@@ -158,6 +158,15 @@ $Q echo "building $(or $(2), $(notdir $(1))) from internal/tools/go.mod..."
 $Q cd internal/tools; go build -mod=readonly -o ../../$(BIN)/$(or $(2), $(notdir $(1))) $(1)
 endef
 
+# renames original binary $(BIN)/<binary> to $(BIN)/<binary>.bin
+# and copy an associated script from ./scripts/gogenerate/<binary>.sh to $(BIN)/<binary>
+#
+# it is used when we want to replace an original binary with a gogenerate script
+define replace_go_generate_script
+$Q mv $(BIN)/$(1) $(BIN)/$(1).bin
+$Q cp ./scripts/gogenerate/$(1).sh $(BIN)/$(1)
+endef
+
 # same as go_build_tool, but uses our main module file, not the tools one.
 # this is necessary / useful for tools that we are already importing in the repo, e.g. yarpc.
 # versions here are checked to make sure the tools version matches the service version.
@@ -183,6 +192,7 @@ $(BIN)/thriftrw-plugin-yarpc: go.mod go.work
 
 $(BIN)/mockgen: internal/tools/go.mod go.work
 	$(call go_build_tool,go.uber.org/mock/mockgen)
+	$(call replace_go_generate_script,mockgen)
 
 $(BIN)/mockery: internal/tools/go.mod go.work
 	$(call go_build_tool,github.com/vektra/mockery/v2,mockery)
@@ -200,6 +210,7 @@ $(BIN)/goimports: internal/tools/go.mod go.work
 
 $(BIN)/gowrap: go.mod go.work
 	$(call go_build_tool,github.com/hexdigest/gowrap/cmd/gowrap)
+	$(call replace_go_generate_script,gowrap)
 
 $(BIN)/revive: internal/tools/go.mod go.work
 	$(call go_build_tool,github.com/mgechev/revive)

scripts/gogenerate/README.md

@@ -0,0 +1,48 @@
+# GoGenerate
+
+This folder contains custom scripts designed to replace the original binaries invoked during `go generate` commands.
+
+## Why do we need these scripts?
+
+In many cases, regenerating files during `go generate` is unnecessary if the source files (or other dependencies) have
+not been updated.
+These scripts introduce a simple optimization: they check file modification times and skip regeneration if the output
+file is already up-to-date.
+
+## How It Works
+
+1. Each script should be called by `make go-generate` or `make pr`
+    1. Directly by `go generate` command will not work, because it will call the original binary that is not replaced by
+       the script
+2. Each script intercepts the call to its respective binary (e.g., `mockgen`, `gowrap`) during `go generate`.
+3. Before running the original command, the script checks:
+    - If the destination file is newer than its dependencies (e.g., source files, templates).
+    - If so, it skips regeneration and exits early.
+4. If regeneration is necessary (i.e., dependencies are newer), the script executes the original binary with all
+   provided arguments.
+
+## How to Debug
+
+1. To enable debug logs run `GO_GENERATE_SCRIPTS_DEBUG=true make go generate ./...`.
+2. Be sure that your script support this flag
+
+## Add a new script
+
+1. Save a new script in this folder with a name matching its corresponding binary (e.g., `mockgen.sh`, `gowrap.sh`).
+2. Make them executable: `chmod +x script.sh`.
+3. Add `replace_go_generate_script` to the `$(BIN)/<script>` section in Makefile
+    1. An original binary will be renamed to `<binary>.bin` and the new script will be copied to `./build/bin`.
+4. Run `make clean` to remove the old binaries.
+5. Run `make go-generate` to generate the new binaries
+
+## Example Scripts
+
+### `mockgen.sh`
+
+Replaces the `mockgen` binary. It checks if the generated mock file is newer than the source file (`$GOFILE`). If so, it
+skips regeneration.
+
+### `gowrap.sh`
+
+Replaces the `gowrap` binary. It ensures that the destination file is newer than both `$GOFILE` and the template file
+before running the original `gowrap` command.

scripts/gogenerate/gowrap.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+
+# Initialize variables
+destinationFile=""
+templateFile=""
+
+# Parse arguments to find the -o (output) and -t (template) arguments
+for ((i = 1; i <= $#; i++)); do
+    if [[ "${!i}" == "-o" ]]; then
+        # Capture the value of the -o argument (destination file)
+        nextIndex=$((i + 1))
+        destinationFile="${!nextIndex}"
+    elif [[ "${!i}" == "-t" ]]; then
+        # Capture the value of the -t argument (template file)
+        nextIndex=$((i + 1))
+        templateFile="${!nextIndex}"
+    fi
+done
+
+# Ensure destinationFile and templateFile are set
+if [[ -z "$destinationFile" ]]; then
+    echo "Error: -o (output) argument is required."
+    exit 1
+fi
+
+if [[ -z "$templateFile" ]]; then
+    echo "Error: -t (template) argument is required."
+    exit 1
+fi
+
+# Check if destinationFile is newer than $GOFILE and templateFile
+if [[ "$destinationFile" -nt "$GOFILE" && "$destinationFile" -nt "$templateFile" ]]; then
+    if [[ "$GO_GENERATE_SCRIPTS_DEBUG" == "true" ]]; then
+        echo "Skipped gowrap for $GOFILE"
+    fi
+    exit 0
+fi
+
+ if [[ "$GO_GENERATE_SCRIPTS_DEBUG" == "true" ]]; then
+        echo "Run gowrap for $GOFILE"
+    fi
+
+# Execute the original gowrap command with all arguments
+gowrap.bin "$@"

scripts/gogenerate/mockgen.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# Initialize variables
+destinationFile=""
+
+# Parse arguments to find the -destination argument
+for arg in "$@"; do
+    if [[ "$arg" == "-destination" ]]; then
+        # Handle the case where -destination is followed by a separate value
+        nextIsDestination=true
+    elif [[ "$arg" == -destination=* ]]; then
+        # Handle the case where -destination=value is used
+        destinationFile="${arg#-destination=}"
+    elif [[ "$nextIsDestination" == true ]]; then
+        # Capture the value after -destination
+        destinationFile="$arg"
+        nextIsDestination=false
+    fi
+done
+
+# Ensure destinationFile is set
+if [[ -z "$destinationFile" ]]; then
+    echo "Error: -destination argument is required."
+    exit 1
+fi
+
+# Check if destinationFile is newer than $GOFILE
+if [[ "$destinationFile" -nt "$GOFILE" ]]; then
+    if [[ "$GO_GENERATE_SCRIPTS_DEBUG" == "true" ]]; then
+      echo "Skipped mockgen for $GOFILE"
+    fi
+    exit 0
+fi
+
+if [[ "$GO_GENERATE_SCRIPTS_DEBUG" == "true" ]]; then
+    echo "Run mockgen for $GOFILE"
+fi
+
+# Execute the original mockgen command with all arguments
+# -write_command_comment=false to remove adding command comment
+mockgen.bin "$@" -write_command_comment=false