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Add mutex to getSnapState to prevent concurrent decryption #3234

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Merged
FrederikBolding merged 3 commits into from
Mar 25, 2025
Merged

Add mutex to getSnapState to prevent concurrent decryption #3234

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e2341b1
Add mutex to `getSnapState` to prevent concurrent decryption
Mrtenz Mar 14, 2025
d85a70b
Add missing async
Mrtenz Mar 14, 2025
64549e3
Update coverage
Mrtenz Mar 14, 2025
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2 changes: 1 addition & 1 deletion packages/snaps-controllers/coverage.json
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"branches": 93.34,
"functions": 97.36,
"functions": 97.37,
"lines": 98.33,
"statements": 98.07
}
49 changes: 29 additions & 20 deletions packages/snaps-controllers/src/snaps/SnapController.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -286,6 +286,11 @@ export type SnapRuntimeData = {
* A mutex to prevent concurrent state updates.
*/
stateMutex: Mutex;

/**
* A mutex to prevent concurrent state decryption.
*/
getStateMutex: Mutex;
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@FrederikBolding FrederikBolding Mar 24, 2025

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Wondering if we could re-use the stateMutex

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@Mrtenz Mrtenz Mar 24, 2025

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It could, but I'm not sure if it should? We can do encryption and decryption at the same time, they don't depend on each other.

};

export type SnapError = {
Expand Down Expand Up @@ -2046,33 +2051,36 @@ export class SnapController extends BaseController<
*/
async getSnapState(snapId: SnapId, encrypted: boolean): Promise<Json> {
const runtime = this.#getRuntimeExpect(snapId);
const cachedState = encrypted ? runtime.state : runtime.unencryptedState;
return await runtime.getStateMutex.runExclusive(async () => {
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@FrederikBolding FrederikBolding Mar 24, 2025 •
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With this cached requests would still have to queue to access the cache, right? That seems less than ideal 🤔

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@hmalik88 hmalik88 Mar 24, 2025

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Would it work if we have a cacheMutex that nests this one?

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@Mrtenz Mrtenz Mar 24, 2025

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What do you mean by nesting in this case?

With this cached requests would still have to queue to access the cache, right? That seems less than ideal 🤔

Yeah, but cached access should be much quicker, so I don't think it's a big issue?

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@FrederikBolding FrederikBolding Mar 25, 2025

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Let's try this as-is and we can always move some logic outside of the mutex block

const cachedState = encrypted ? runtime.state : runtime.unencryptedState;

if (cachedState !== undefined) {
return cachedState;
}
if (cachedState !== undefined) {
return cachedState;
}

const state = encrypted
? this.state.snapStates[snapId]
: this.state.unencryptedSnapStates[snapId];
const state = encrypted
? this.state.snapStates[snapId]
: this.state.unencryptedSnapStates[snapId];

if (state === null || state === undefined) {
return null;
}
if (state === null || state === undefined) {
return null;
}

if (!encrypted) {
// For performance reasons, we do not validate that the state is JSON,
// since we control serialization.
const json = JSON.parse(state);
runtime.unencryptedState = json;
if (!encrypted) {
// For performance reasons, we do not validate that the state is JSON,
// since we control serialization.
const json = JSON.parse(state);
runtime.unencryptedState = json;

return json;
}
return json;
}

const decrypted = await this.#decryptSnapState(snapId, state);
runtime.state = decrypted;
const decrypted = await this.#decryptSnapState(snapId, state);
// eslint-disable-next-line require-atomic-updates
runtime.state = decrypted;

return decrypted;
return decrypted;
});
}

/**
Expand Down Expand Up @@ -3968,6 +3976,7 @@ export class SnapController extends BaseController<
interpreter,
stopping: false,
stateMutex: new Mutex(),
getStateMutex: new Mutex(),
});
}

Expand Down
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