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Internal debugging API

The Marine SDK has an internal feature called debug, it allows debugging some of the internal details of the IT execution.

Enabling debug API​

To enable logging please specify the logger feature of the Marine SDK in Config.toml:

toml
[dependencies]
marine-rs-sdk = { version = "0.7.1", features = ["debug"] }
toml
[dependencies]
marine-rs-sdk = { version = "0.7.1", features = ["debug"] }

Using debug API​

Normally, this feature should not be used by a backend developer. Below you can see examples of such details for the greeting service compiled with the debug feature. Please note, that it's necessary to run REPL with RUST_LOG.

sh
# running the greeting service compiled with debug feature
RUST_LOG="info" mrepl Config.toml
Welcome to the Marine REPL (version 0.16.0)
Minimal supported versions
  sdk: 0.6.0
  interface-types: 0.20.0
app service was created with service id = 0ba05b05-4e92-48bf-ac30-2b8b59efe189
elapsed time 746.509µs
1> call greeting greeting "user"
[greeting] sdk.allocate: 4
[greeting] sdk.set_result_ptr: 1114240
[greeting] sdk.set_result_size: 8
[greeting] sdk.get_result_ptr, returns 1114240
[greeting] sdk.get_result_size, returns 8
[greeting] sdk.get_result_ptr, returns 1114240
[greeting] sdk.get_result_size, returns 8
[greeting] sdk.deallocate: 0x110080 8
result: String("Hi, user")
 elapsed time: 222.675µs
sh
# running the greeting service compiled with debug feature
RUST_LOG="info" mrepl Config.toml
Welcome to the Marine REPL (version 0.16.0)
Minimal supported versions
  sdk: 0.6.0
  interface-types: 0.20.0
app service was created with service id = 0ba05b05-4e92-48bf-ac30-2b8b59efe189
elapsed time 746.509µs
1> call greeting greeting "user"
[greeting] sdk.allocate: 4
[greeting] sdk.set_result_ptr: 1114240
[greeting] sdk.set_result_size: 8
[greeting] sdk.get_result_ptr, returns 1114240
[greeting] sdk.get_result_size, returns 8
[greeting] sdk.get_result_ptr, returns 1114240
[greeting] sdk.get_result_size, returns 8
[greeting] sdk.deallocate: 0x110080 8
result: String("Hi, user")
 elapsed time: 222.675µs

The most important information these logs relates to the allocate/deallocate function calls. The sdk.allocate: 4 line corresponds to passing the 4-byte user string to the Wasm module, with the memory allocated inside the module, and the string is copied there. Whereas sdk.deallocate: 0x110080 8 refers to passing the 8-byte resulting string Hi, user to the host side. Since all arguments and results are passed by value, deallocate is called to delete unnecessary memory inside the Wasm module.