The host circuits contains two components. The operands selection circuit which select the target opcodes and the host function constraint circuit which enforces the semantics of a specific host function.
Suppose we have a host calling trace that calls two functions
a(x,y) = x + y + 1
b(x,y,z) = x * y * z
It follows that the shared host op table will looks like the following:
| op_code | arg | idx |
|---|---|---|
| 0 | 0 | 0 |
| op_a | a_0 | 1 |
| op_a | a_1 | 2 |
| op_a | a_r | 3 |
| op_b | b_0 | 4 |
| op_b | b_1 | 5 |
| op_b | b_2 | 6 |
| op_b | b_r | 7 |
Thus, to implement the selection circuit for function b then the following should be the filtered result
| op_code | arg_sel | idx_sel |
|---|---|---|
| op_b | 4 | |
| op_b | 5 | |
| op_b | 6 | |
| op_b | 7 |
There are two async backend for mongodb: mongo-std-sync and mongo-tokio-sync(default). Note that when using the non-default backendmongo-std-sync, you must also using default-features = false.