wasm-pre-init

Quick and dirty testing wizer against wasm binaries built with rust and ran using wazero runtime.

Spoiler: it works perfectly :)

Explanation

wizer is a pre-initializer for Wasm - think wasm-opt.

This would allow you to do something resource intensive at build time, rather than runtime. For example, you could pre-initialize multiple regexes that are normally quite expensive.

This Test

This test verifies that wizer works with wasm artifacts produced by wazero.

There are two test cases:

wasm-regex and wasm-sleep

wasm-regex

This test case has two wasm files - wasm-regex-regular.wasm and wasm-regex-init.wizer.wasm.

• *regular* contains regex init code directly in the _start() func.
• *init.wizer* contains regex init code in the init() func.

make run will show how long wazero run ... took to run both of the wasm files.

time isn't precise enough to give a definitive answer as to what's faster, so need another more test that gives us a clearer picture.

wasm-sleep

In this case, *regular.wasm will sleep for 5s before printing "John Doe". *init.wizer.wasm will sleep for 5s in the init() func and print "John Doe" in the _start() func.

Same as with wasm-regex:

• *regular* contains sleep code directly in the _start() func.
• *init.wizer* contains sleep code in the init() func.

You should see that *init.wizer.wasm will take <1s to run while *regular.wasm will take >5s.

Result

~/Code/streamdal/wasm-pre-init master*                                                                                                                                                 ◒
❯ make run
Testing wasm-regex-regular...
time wazero run -env NUM=123 build/wasm_regex_regular.wasm
Matched!
        3.52 real         3.49 user         0.03 sys
Testing wasm-regex-init...
time wazero run -env NUM=123 build/wasm_regex_init.wizer.wasm
Matched!
        3.48 real         3.46 user         0.02 sys
Testing wasm-sleep-regular...
time wazero run build/wasm_sleep_regular.wasm
Name: John Doe
        5.07 real         0.06 user         0.01 sys
Testing wasm-sleep-init...
time wazero run build/wasm_sleep_init.wizer.wasm
Name: John Doe
        0.07 real         0.06 user         0.01 sys

Setup

1. Install wazero CLI binary; install wizer via cargo.
2. Run make build <- this will create .wasm artifacts in ./build/*
3. Run make run <- this will perform time wazero run ... on each one of the wasm files in the ./build dir.