Initial Memory Size

[ernst1j]

We have found an issue when loading large policies causing the Wasmtime to throw a "wasm trap: out of bounds memory access" error. We were able to pull in the source code into our project and change the minimum memory page size from 2 to 3 and that resolved our issue. We also tried updating the maximum memory size, but that did not seem to resolve the issue.

Unless we are doing something wrong, we would like to have an optional parameter on the CreatePolicyInstance to be able to specify the initial page size.

[christophwille]

I can add a ctor parameter for that; could you tell me actually which line raised the wasm trap (curiosity)?

[christophwille]

Does the change in the linked commit work for you?

[ernst1j]

@christophwille, yes that will work great. Thanks for the quick response.

[ernst1j]

FYI: This is my stack trace from the error: Wasmtime.TrapException: wasm trap: out of bounds memory access
at Wasmtime.Linker.Instantiate(Store store, Module module)
at Opa.Wasm.OpaPolicy.Initialize(Module module) in //src/Opa.Wasm/OpaPolicy.cs:line 119
at Opa.Wasm.OpaPolicy..ctor(Engine engine, Module module, IOpaSerializer serializer) in //src/Opa.Wasm/OpaPolicy.cs:line 48
at Opa.Wasm.OpaPolicyModule.CreatePolicyInstance(IOpaSerializer serializer) in /_/src/Opa.Wasm/OpaPolicyModule.cs:line 23