fix(xsnap): take snapshot without impact on GC #3607

Moddable reworked the chunk allocator to always use a single memory block for chunk storage.

The change is implemented in `xsnapPlatform.c`. The implementation uses `mmap`/`mprotect` (`VirtualAlloc` on Windows) to reserve and to commit memory pages. 

To get this fix, we add an `xsnap-native` submodule that replaces `xsnap.c` and friends.
The submodule includes a few tweaks: https://github.com/agoric-labs/xsnap-pub/tree/endo-submodule

fixes #3577
fixes #3139 , bringing us back to stock XS.
fixes #2469 - Moddable reviewed the code well enough to substantially re-work it.

.github/workflows/docker.yml

@@ -14,17 +14,15 @@ jobs:
       run: echo "GIT_REVISION=$(git rev-parse HEAD)" >> $GITHUB_ENV
     - name: Save SDK_VERSION
       run: echo "SDK_VERSION=$(jq -r .version package.json)" >> $GITHUB_ENV
-    - name: Save MODDABLE_COMMIT_HASH, MODDABLE_URL
+    - name: Save commit hash, url of submodules to environment
       run: |
-        git submodule status packages/xsnap/moddable | \
-        sed -ne 's/^.\([^ ]*\).*/MODDABLE_COMMIT_HASH=\1/p' >> $GITHUB_ENV
-        sed -ne 's!^.*url = \(https://.*moddable\.git\).*!MODDABLE_URL=\1!p' .gitmodules >> $GITHUB_ENV
+        node packages/xsnap/src/build.js --show-env >> $GITHUB_ENV
     - name: Build SDK image
       uses: elgohr/Publish-Docker-Github-Action@master
       with:
         name: agoric/agoric-sdk
         dockerfile: packages/deployment/Dockerfile.sdk
-        buildargs: MODDABLE_COMMIT_HASH,MODDABLE_URL,GIT_REVISION
+        buildargs: MODDABLE_COMMIT_HASH,MODDABLE_URL,XSNAP_NATIVE_COMMIT_HASH,XSNAP_NATIVE_URL,GIT_REVISION
         username: ${{ secrets.DOCKER_USERNAME }}
         password: ${{ secrets.DOCKER_PASSWORD }}
         snapshot: true

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "packages/xsnap/moddable"]
 	path = packages/xsnap/moddable
 	url = https://github.com/agoric-labs/moddable.git
+[submodule "packages/xsnap/xsnap-native"]
+	path = packages/xsnap/xsnap-native
+	url = https://github.com/agoric-labs/xsnap-pub

packages/deployment/Makefile

@@ -4,9 +4,6 @@ SS := ../cosmic-swingset/
 VERSION := $(shell node -e 'console.log(require("../../package.json").version)' 2>/dev/null)
 
 TAG := $(if $(VERSION),$(VERSION),latest)
-MODDABLE_COMMIT_HASH := $(shell git submodule status ../xsnap/moddable | \
-	sed -ne 's/^.\([^ ]*\).*/\1/p')
-MODDABLE_URL := $(shell sed -ne 's!^.* = \(https://.*moddable\.git\).*!\1!p' ../../.gitmodules)
 GIT_REVISION := $(shell hash=$$(git rev-parse --short HEAD); \
 	dirty=`git diff --quiet || echo -dirty`; \
 	echo "$$hash$$dirty")
@@ -18,6 +15,9 @@ else
 DONT_PUSH_LATEST := $(if $(findstring -,$(TAG)),:,)
 endif
 
+submodule.env: ../xsnap/moddable/src/build.js
+	node ../xsnap/moddable/src/build.js --show-env >$@
+
 docker-show-fat:
 	date > show-fat-bust-cache.stamp
 	docker build --file=Dockerfile.show-fat ../..
@@ -28,6 +28,8 @@ docker-build: docker-build-sdk docker-build-solo \
 docker-build-sdk:
 	docker build --build-arg=MODDABLE_COMMIT_HASH=$(MODDABLE_COMMIT_HASH) \
 		--build-arg=MODDABLE_URL=$(MODDABLE_URL) \
+		--build-arg=XSNAP_NATIVE_COMMIT_HASH=$(XSNAP_NATIVE_COMMIT_HASH) \
+		--build-arg=XSNAP_NATIVE_URL=$(XSNAP_NATIVE_URL) \
 		--build-arg=GIT_REVISION=$(GIT_REVISION) \
 		-t $(REPOSITORY_SDK):$(TAG) --file=Dockerfile.sdk ../..
 	docker tag $(REPOSITORY_SDK):$(TAG) $(REPOSITORY_SDK):latest
@@ -73,3 +75,5 @@ docker-push-solo:
 docker-push-deployment:
 	$(DONT_PUSH_LATEST) docker push agoric/deployment:latest
 	docker push agoric/deployment:$(TAG)
+
+-include submodule.env

packages/xsnap/api.js

@@ -3,7 +3,7 @@
 /** The version identifier for our meter type.
  * TODO Bump this whenever there's a change to metering semantics.
  */
-export const METER_TYPE = 'xs-meter-9';
+export const METER_TYPE = 'xs-meter-10';
 
 export const ExitCode = {
   E_UNKNOWN_ERROR: -1,

packages/xsnap/doc/README.md

@@ -0,0 +1,9 @@
+See also [xsnap documentation][1] including:
+
+ - [XS Metering][2]
+ - [XS Snapshots][3]
+
+
+[1]: https://github.com/agoric-labs/xsnap-pub/blob/endo-submodule/xsnap/documentation/
+[2]: https://github.com/agoric-labs/xsnap-pub/blob/endo-submodule/xsnap/documentation/XS%20Metering.md
+[3]: https://github.com/agoric-labs/xsnap-pub/blob/endo-submodule/xsnap/documentation/XS%20Snapshots.md