cc-lb-runtime-wasmtime 0.1.2

Wasmtime-based plugin runtime for cc-lb. Host-side wasm plugin admission + dispatch.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141

use wasmtime::{Instance, Memory, Store, TypedFunc};

use crate::cell::PluginCell;
use crate::engine::HostState;
use crate::error::WasmtimeRuntimeError;

use super::HookFn;

pub(super) struct WorkerInstance {
    pub(super) store: Store<HostState>,
    pub(super) memory: Memory,
    pub(super) alloc_fn: TypedFunc<(u32, u32), u32>,
    pub(super) free_fn: TypedFunc<(u32, u32, u32), ()>,
    pub(super) filter_fn: Option<TypedFunc<(u32, u32), u64>>,
    pub(super) shape_fn: Option<TypedFunc<(u32, u32), u64>>,
    pub(super) observe_fn: Option<TypedFunc<(u32, u32), u64>>,
    pub(super) transform_response_fn: Option<TypedFunc<(u32, u32), u64>>,
    pub(super) transform_sse_event_fn: Option<TypedFunc<(u32, u32), u64>>,
}

pub(super) fn build_worker_instance(
    cell: &PluginCell,
    hook: HookFn,
) -> Result<WorkerInstance, WasmtimeRuntimeError> {
    let engine = cell.instance_pre.module().engine();
    let mut store = Store::new(engine, HostState::new(cell.memory_max_pages));
    store.limiter(|state| state.limits());

    let instance: Instance = cell.instance_pre.instantiate(&mut store).map_err(|e| {
        if e.downcast_ref::<wasmtime::PoolConcurrencyLimitError>()
            .is_some()
        {
            WasmtimeRuntimeError::PoolSaturated { resource: "pool" }
        } else {
            WasmtimeRuntimeError::InstantiateFailed(anyhow::Error::from(e))
        }
    })?;

    let memory = instance.get_memory(&mut store, "memory").ok_or_else(|| {
        WasmtimeRuntimeError::ModuleRejected {
            reason: "module does not export `memory`".into(),
        }
    })?;

    let alloc_fn = instance
        .get_typed_func::<(u32, u32), u32>(&mut store, "cc_lb_alloc")
        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
            reason: format!("missing or mistyped `cc_lb_alloc` export: {e}"),
        })?;

    let free_fn = instance
        .get_typed_func::<(u32, u32, u32), ()>(&mut store, "cc_lb_free")
        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
            reason: format!("missing or mistyped `cc_lb_free` export: {e}"),
        })?;

    let (filter_fn, shape_fn, observe_fn, transform_response_fn, transform_sse_event_fn) =
        match hook {
            HookFn::Filter => (
                Some(
                    instance
                        .get_typed_func::<(u32, u32), u64>(&mut store, "cc_lb_filter")
                        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
                            reason: format!("missing or mistyped `cc_lb_filter` export: {e}"),
                        })?,
                ),
                None,
                None,
                None,
                None,
            ),
            HookFn::Shape => (
                None,
                Some(
                    instance
                        .get_typed_func::<(u32, u32), u64>(&mut store, "cc_lb_shape")
                        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
                            reason: format!("missing or mistyped `cc_lb_shape` export: {e}"),
                        })?,
                ),
                None,
                None,
                None,
            ),
            HookFn::Observe => (
                None,
                None,
                Some(
                    instance
                        .get_typed_func::<(u32, u32), u64>(&mut store, "cc_lb_observe")
                        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
                            reason: format!("missing or mistyped `cc_lb_observe` export: {e}"),
                        })?,
                ),
                None,
                None,
            ),
            HookFn::TransformResponse => (
                None,
                None,
                None,
                Some(
                    instance
                        .get_typed_func::<(u32, u32), u64>(&mut store, "cc_lb_transform_response")
                        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
                            reason: format!(
                                "missing or mistyped `cc_lb_transform_response` export: {e}"
                            ),
                        })?,
                ),
                None,
            ),
            HookFn::TransformSseEvent => (
                None,
                None,
                None,
                None,
                Some(
                    instance
                        .get_typed_func::<(u32, u32), u64>(&mut store, "cc_lb_transform_sse_event")
                        .map_err(|e| WasmtimeRuntimeError::ModuleRejected {
                            reason: format!(
                                "missing or mistyped `cc_lb_transform_sse_event` export: {e}"
                            ),
                        })?,
                ),
            ),
        };

    Ok(WorkerInstance {
        store,
        memory,
        alloc_fn,
        free_fn,
        filter_fn,
        shape_fn,
        observe_fn,
        transform_response_fn,
        transform_sse_event_fn,
    })
}