Add bundled distribution of SWIPL

[jeswr]

Following on from the recent discussion in #1; this modifies the build to create a swipl-bundle.js file that contains everything needed to run swipl in browser and node. I have also made this the main entry point as there currently is none.

---

I've calculated that the size of swipl-bundle.js is 33.5% larger than the combination of swipl-web.wasm, swipl-web.data and swipl-web.js. And it seems to run pretty fast once loaded. I personally think this is acceptable for the type of POC use-cases that I am working on.

2M swipl-web.wasm
6M swipl-web.data
1M swipl-web.js
=9M

11M swipl-bundle.js

[rla]

This code seems to be unused and leftover from testing?

[jeswr]

That file is from the first commit of this PR - and has already been removed. This is the diff I am seeing for the whole PR

[rla]

Would be nice to integrate this into swipl-devel so we won't need a patch but just different build flags. Or even better, build all 3 variants at the same time: web, node, and single-file.

[jeswr]

That file is no longer part of this PR. Instead the same outcome is achieved by making the following update to the dockerfile https://github.com/rla/npm-swipl-wasm/blob/f4eee5e8c895ca6fe93d55506000323d05d380e8/docker/Dockerfile#L69-L77

[jeswr]

Or even better, build all 3 variants at the same time: web, node, and single-file.

I'm not really familiar with the cmake toolchain so it is probably faster for you or @JanWielemaker to do it; rather than go through a review process with my attempts. I imagine that EmscriptenTargets.cmake should updated to look something like this; but I'm also sure there is a cleaner way of doing it.

# Make console binaries runnable through Node.js.

set(WASM_NODE_LINK_FLAGS
    -s NODERAWFS=1
    -s EXIT_RUNTIME=1)
join_list(WASM_NODE_LINK_FLAGS_STRING " " ${WASM_NODE_LINK_FLAGS})

set_target_properties(swipl PROPERTIES
		      LINK_FLAGS "${WASM_NODE_LINK_FLAGS_STRING}")

# Create the preload data containing the libraries. Note that
# alternatively we can put the library in the resource file and
# link the resource file into the main executable.

set(WASM_BOOT_FILE "${WASM_PRELOAD_DIR}/boot.prc")
add_custom_command(
    OUTPUT ${WASM_BOOT_FILE}
    COMMAND ${CMAKE_COMMAND} -E make_directory ${WASM_PRELOAD_DIR}
    COMMAND ${CMAKE_COMMAND} -E copy ${SWIPL_BOOT_FILE} ${WASM_BOOT_FILE}
    COMMAND ${CMAKE_COMMAND} -E copy_directory
			     ${SWIPL_BUILD_LIBRARY} ${WASM_PRELOAD_DIR}/library
    DEPENDS ${SWIPL_BOOT_FILE} prolog_home library_index
    VERBATIM)

add_custom_target(wasm_preload_dir DEPENDS ${WASM_BOOT_FILE})
add_dependencies(wasm_preload wasm_preload_dir)

# Build the browser-deployed binary with a bit different linker flags.

set(POSTJS ${CMAKE_CURRENT_SOURCE_DIR}/wasm/prolog.js)
set(PREJS ${CMAKE_CURRENT_SOURCE_DIR}/wasm/pre.js)

set(WASM_SHARED_LINK_FLAGS
    -s WASM=1
    -s MODULARIZE=1
    -s EXPORT_NAME=SWIPL
    -s NO_EXIT_RUNTIME=0
    -s WASM_BIGINT=1
    -s ALLOW_MEMORY_GROWTH=1
    -s EXPORTED_FUNCTIONS=@${CMAKE_SOURCE_DIR}/src/wasm/exports.json
    -s EXPORTED_RUNTIME_METHODS=@${CMAKE_SOURCE_DIR}/src/wasm/runtime_exports.json
    --pre-js ${PREJS}
    --post-js ${POSTJS})

if(MULTI_THREADED)
  list(APPEND WASM_SHARED_LINK_FLAGS
       -pthread
       -s PTHREAD_POOL_SIZE=4)
endif()

set(WASM_WEB_LINK_FLAGS
    --preload-file ${WASM_PRELOAD_DIR}@swipl)
list(APPEND WASM_WEB_LINK_FLAGS WASM_SHARED_LINK_FLAGS)

set(WASM_BUNDLE_LINK_FLAGS
    -s SINGLE_FILE
    --embed-file ${WASM_PRELOAD_DIR}@swipl)
list(APPEND WASM_BUNDLE_LINK_FLAGS WASM_SHARED_LINK_FLAGS)

join_list(WASM_WEB_LINK_FLAGS_STRING " " ${WASM_WEB_LINK_FLAGS})
join_list(WASM_BUNDLE_LINK_FLAGS_STRING " " ${WASM_WEB_LINK_FLAGS})

add_executable(swipl-web ${SWIPL_SRC})
set_target_properties(swipl-web PROPERTIES
		      LINK_FLAGS "${WASM_WEB_LINK_FLAGS_STRING}")
target_link_libraries(swipl-web libswipl)
add_dependencies(swipl-web wasm_preload)
set_property(TARGET swipl-web PROPERTY LINK_DEPENDS
	     ${POSTJS} ${PREJS})

add_executable(swipl-bundle ${SWIPL_SRC})
set_target_properties(swipl-bundle PROPERTIES
              LINK_FLAGS "${WASM_WEB_LINK_FLAGS_STRING}")
target_link_libraries(swipl-bundle libswipl)
add_dependencies(swipl-bundle wasm_preload)
set_property(TARGET swipl-bundle PROPERTY LINK_DEPENDS
         ${POSTJS} ${PREJS})

[JanWielemaker]

I'm a little lost. Would it be a good option to have a CMake option that selects between the various build options?

[jeswr]

I'm a little lost. Would it be a good option to have a CMake option that selects between the various build options?

As far as I'm concerned that is overkill and it is fine to always just build all 3 variants; which would mean that the change compared to the current CMake configuration to also emit swipl-bundle.js which is produced using the same parameters as the swipl-web files with the additional flags

    -s SINGLE_FILE
    --embed-file ${WASM_PRELOAD_DIR}@swipl)

and without the flag

   --preload-file ${WASM_PRELOAD_DIR}@swipl)

[rla]

@JanWielemaker, @jeswr since we already build both browser and node variants always then lets build single-file variant too. I think that the cmake file updates proposed by Jesse look fine.

I would also like to have following updates in this package:

• Add README example with importing directly from swipl-wasm. I see that Node example
  lacks import completely. I will update README myself. Also couple of words why we provide
  3 different modules. (@rla)
• Test case for node and browser that loads code from -bundle version.

Should we also change the SWI-Prolog own documentation? (https://www.swi-prolog.org/pldoc/man?section=wasm-loading).

I have received very little feedback on using the WebAssembly version. Only Jesse has sent me feedback and long time ago a newer builds were asked on the forum but that's all. So it's very difficult to make decisions.

[JanWielemaker]

I have received very little feedback on using the WebAssembly version.

I have no clue on the popularity. The WASM shell got about 60 users per day before holidays (now 20-30). For use with Node there are also interfaces to the real thing while the WASM version is still pretty limited and slow when compared to the real thing.

I'll have a look at this, probably next week. The more PRs the better 😄

[rla]

I took these changes and combined them with recent swipl-devel changes. I added small description to README on bundle usage and released a new version on NPM.