Deprecate default onEnd, allow returning from onResult, refactor/fix error handling, fix duplicate onEnd calls

master
Sven Slootweg 3 years ago
parent fe3e2c780f
commit ea3968b240

@ -1,6 +1,8 @@
"use strict";
const Promise = require("bluebird");
const createResultBuffer = require("result-buffer");
const propagateAbort = require("@promistream/propagate-abort");
const propagatePeek = require("@promistream/propagate-peek");
const isEndOfStream = require("@promistream/is-end-of-stream");
@ -9,7 +11,6 @@ const isAborted = require("@promistream/is-aborted");
const { validateOptions } = require("@validatem/core");
const required = require("@validatem/required");
const isFunction = require("@validatem/is-function");
const defaultTo = require("@validatem/default-to");
const wrapValueAsOption = require("@validatem/wrap-value-as-option");
// FIXME: Update other stream implementations to new API
@ -20,20 +21,18 @@ module.exports = function simpleSinkStream(_options) {
onResult: [ required, isFunction ],
onAbort: [ isFunction ],
onSourceChanged: [ isFunction ],
onEnd: [ isFunction, defaultTo.literal(function defaultOnEnd() {
// FIXME: Deprecate this, it does not work as-expected when the onResult callback never gets called (eg. due to a stream immediately terminating), as the onResult callback will then never get a chance to set the lastResult, not even to an initializer value (eg. an empty array for `collect`)
// We return whatever value we got last from the specified onResult callback.
return lastResult;
})]
onEnd: [ isFunction ]
}
]);
let lastResult;
// FIXME: Bump minor version!
let onEndCalled = false;
let onEndResult;
let abortHandled = false;
let lastKnownSource;
let resultBuffer = createResultBuffer();
return {
_promistreamVersion: 0,
description: `simple sink stream`,
@ -45,72 +44,85 @@ module.exports = function simpleSinkStream(_options) {
return source.read();
}).then((value) => {
// FIXME: Document that you can pause the sink from the onResult callback, by returning a Promise that resolves when it should be resumed
return onResult(value);
return onResult(value, source.abort.bind(source));
}).then((result) => {
lastResult = result;
return attemptRead();
// FIXME: Replace all instances of undefined checks with a standardized NoValue marker
if (result !== undefined) {
// TODO: Force end of stream when this occurs?
return result;
} else {
return attemptRead();
}
});
}
return Promise.try(() => {
if (source !== lastKnownSource && onSourceChanged != null) {
lastKnownSource = source;
return onSourceChanged(source);
}
}).then(() => {
return attemptRead();
}).catch(isEndOfStream, () => {
/* Don't attempt to do another read, we're done. */
// FIXME: Is it actually correct to keep returning the same thing?
if (onEndCalled) {
return onEndResult;
} else {
return Promise.try(() => {
return onEnd();
}).then((result) => {
onEndResult = result;
return result;
});
}
}).catch((error) => !isAborted(error), (error) => {
return resultBuffer.maybeRead(() => {
return Promise.try(() => {
return source.abort(error);
}).catch((abortError) => {
let message = [
`Tried to abort stream due to encountering an error, but the aborting itself failed`,
`Original error message: ${error.message}`,
`Abort failure message: ${abortError.message}`
].join("\n");
// FIXME: Make this some sort of chained error
let combinedError = new Error(message);
combinedError.stack = abortError.stack; // HACK
throw combinedError;
if (source !== lastKnownSource && onSourceChanged != null) {
lastKnownSource = source;
return onSourceChanged(source);
}
}).then(() => {
// Pass through the original error to the user
throw error;
});
}).catch(isAborted, (marker) => {
if (abortHandled === false) {
abortHandled = true;
return attemptRead();
}).catch(isEndOfStream, (error) => {
/* Don't attempt to do another read, we're done. */
if (!onEndCalled && onEnd != null) {
onEndCalled = true;
return Promise.try(() => {
return onEnd();
}).then((result) => {
if (result !== undefined) {
resultBuffer.push(result);
}
});
}
return resultBuffer.maybeRead(() => {
throw error;
});
}).catch((error) => !isAborted(error), (error) => {
return Promise.try(() => {
if (onAbort != null) {
return onAbort();
}
return source.abort(error);
}).catch((abortError) => {
let message = [
`Tried to abort stream due to encountering an error, but the aborting itself failed`,
`Original error message: ${error.message}`,
`Abort failure message: ${abortError.message}`
].join("\n");
// FIXME: Make this some sort of chained error
let combinedError = new Error(message);
combinedError.stack = abortError.stack; // HACK
throw combinedError;
}).then(() => {
if (marker.reason instanceof Error) {
// NOTE: This ensures that the original error causing the abort is thrown exactly once
throw marker.reason;
} else {
throw marker;
}
// Pass through the original error to the user
throw error;
});
} else {
// Don't interfere, we only need special behaviour on the first occurrence
throw marker;
}
}).catch(isAborted, (marker) => {
if (abortHandled === false) {
abortHandled = true;
return Promise.try(() => {
if (onAbort != null) {
return onAbort(marker.reason);
}
}).then((value) => {
if (value !== undefined) {
resultBuffer.push(value);
}
if (marker.reason instanceof Error) {
// NOTE: This ensures that the original error causing the abort is thrown exactly once
resultBuffer.push(Promise.reject(marker.reason));
}
});
}
return resultBuffer.maybeRead(() => {
throw marker;
});
});
});
}
};

@ -11,10 +11,10 @@
"@promistream/propagate-abort": "^0.1.6",
"@promistream/propagate-peek": "^0.1.1",
"@validatem/core": "^0.3.11",
"@validatem/default-to": "^0.1.0",
"@validatem/is-function": "^0.1.0",
"@validatem/required": "^0.1.1",
"@validatem/wrap-value-as-option": "^0.1.0",
"bluebird": "^3.5.4"
"bluebird": "^3.5.4",
"result-buffer": "^0.1.0"
}
}

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