ctb: Fix multithreaded test race

`generate-l2-genesis.sh` is causing spurious test failures. The `.testdata/genesis.json` file comes up as zero-length in tests, even when the script checks for its length before exiting. I believe this is because multiple processes are executing the `generate-l2-genesis.sh` file at once, which causes a race condition where different invocations of the script cause the genesis file to be truncated.

This PR attempts to fix the issue by using a temporary directory as a lock to prevent multiple invocations of the `generate-l2-genesis.sh` script from running at the same time. Directory creations are atomic in Bash, so we can use this technique to create a mutex. If the directory can't be created, then the script will assume that another script is writing the genesis file and wait up to 5 minutes for it to be created. The script uses `trap` to delete the mutex directory when it's done.

packages/contracts-bedrock/scripts/generate-l2-genesis.sh

@@ -18,30 +18,59 @@ TESTDATA_DIR="$CONTRACTS_DIR/.testdata"
 
 OUTFILE_L2="$TESTDATA_DIR/genesis.json"
 OUTFILE_ROLLUP="$TESTDATA_DIR/rollup.json"
-mkdir -p "$TESTDATA_DIR"
-
-if [ ! -f "$DEPLOY_ARTIFACT" ]; then
-  forge script $CONTRACTS_DIR/scripts/Deploy.s.sol:Deploy > /dev/null 2>&1
-fi
-
-if [ ! -f "$OUTFILE_L2" ]; then
-  go run $OP_NODE genesis l2 \
-    --deploy-config "$CONTRACTS_DIR/deploy-config/hardhat.json" \
-    --l1-deployments "$DEPLOY_ARTIFACT" \
-    --l1-starting-block "$L1_STARTING_BLOCK_PATH" \
-    --outfile.l2 "$OUTFILE_L2" \
-    --outfile.rollup "$OUTFILE_ROLLUP" > /dev/null 2>&1
-fi
-
-# Wait for the L2 outfile to be over 8M for up to 2 seconds
-# This is a hack to ensure that the outfile is fully written
-# before the solidity tests try to read it
-for i in {1..8}; do
-  if [ $(du -m "$OUTFILE_L2" | cut -f1) -ge 8 ]; then
+
+LOCKDIR="/tmp/lock-generate-l2-genesis"
+
+cleanup() {
+  rm -rf -- "$LOCKDIR"
+}
+
+# Wait for the L2 outfile to be over 8M for up to $2 iterations
+# of $1 seconds. This is a hack to ensure that the outfile is fully
+# written before the solidity tests try to read it
+wait_l2_outfile() {
+  i=1
+  while [ $i -le $2 ]; do
+    i=$(($i + 1))
+
+    if [ ! -f "$OUTFILE_L2" ]; then
+      sleep $1
+      continue
+    fi
+
+    if [ $(du -m "$OUTFILE_L2" | cut -f1) -lt 8 ]; then
+      sleep $1
+      continue
+    fi
+
     exit 0
+  done
+
+  echo "L2 genesis file not generated in time. Exiting."
+  exit 1
+}
+
+# Directory creations are atomic, so we can use mkdir to
+# create a lockfile that prevents subsequent invocations
+# of the script from running concurrently.
+if mkdir -- "$LOCKDIR" > /dev/null 2>&1; then
+  trap 'cleanup' EXIT
+
+  mkdir -p "$TESTDATA_DIR"
+
+  if [ ! -f "$DEPLOY_ARTIFACT" ]; then
+    forge script $CONTRACTS_DIR/scripts/Deploy.s.sol:Deploy > /dev/null 2>&1
   fi
-  sleep 0.25
-done
 
-echo "L2 genesis file not generated in time. Exiting."
-exit 1
+  if [ ! -f "$OUTFILE_L2" ]; then
+    go run $OP_NODE genesis l2 \
\ No newline at end of file
+      --deploy-config "$CONTRACTS_DIR/deploy-config/hardhat.json" \
+      --l1-deployments "$DEPLOY_ARTIFACT" \
+      --l1-starting-block "$L1_STARTING_BLOCK_PATH" \
+      --outfile.l2 "$OUTFILE_L2" \
+      --outfile.rollup "$OUTFILE_ROLLUP" > /dev/null 2>&1
+  fi
+else
+  # Wait up to 5 minutes for the lock to be released
+  wait_l2_outfile 0.25 1200
+fi
\ No newline at end of file