Add debugging, force sequential operation

index.js

@@ -1,13 +1,18 @@
 "use strict";
 
 const Promise = require("bluebird");
-const propagateAbort = require("@promistream/propagate-abort");
 const unreachable = require("@joepie91/unreachable")("@promistream/buffer");
 const util = require("util");
+const debug = require("debug")("promistream:buffer");
+
+const propagateAbort = require("@promistream/propagate-abort");
+const sequentialize = require("@promistream/sequentialize");
+const pipe = require("@promistream/pipe");
 
 module.exports = function bufferStream() {
 	let buffer;
 	let bufferPeeked;
+	let hasPeekedUpstream = false;
 
 	function attemptRead(readFunc) {
 		return Promise.try(() => {
@@ -15,6 +20,8 @@ module.exports = function bufferStream() {
 		}).then((result) => {
 			if (Array.isArray(result)) {
 				if (result.length > 0) {
+					debug(`Buffered ${result.length} items`);
+
 					buffer = result;
 					bufferPeeked = result.map(() => false);
 				} else {
@@ -30,27 +37,59 @@ module.exports = function bufferStream() {
 		});
 	}
 
-	return {
+	function peekLocal() {
+		let unpeekedIndex = bufferPeeked.indexOf(false);
+
+		if (unpeekedIndex >= 0) {
+			bufferPeeked[unpeekedIndex] = true;
+			return true;
+		}
+	}
+
+	function peekUpstream(source) {
+		if (!hasPeekedUpstream) {
+			debug("Peeking upstream");
+			hasPeekedUpstream = true;
+			return source.peek();
+		} else if (buffer == null) {
+			debug("Not allowed to peek upstream, reading first");
+
+			return Promise.try(() => {
+				return attemptRead(source.read);
+			}).then(() => {
+				return peekLocal();
+			});
+		} else {
+			unreachable("Attempted to peek upstream while there is already a local buffer");
+		}
+	}
+
+	let bufferStream = {
 		_promistreamVersion: 0,
 		description: "buffer stream",
 		abort: propagateAbort,
 		peek: function peekValue_bufferedSourceStream(source) {
+			debug("Got peek request");
+
 			if (buffer == null) {
-				return source.peek();
+				debug("No buffer, forwarding peek to upstream");
+				return peekUpstream(source);
 			} else {
-				let unpeekedIndex = bufferPeeked.indexOf(false);
+				if (peekLocal()) {
-
+					debug("Answering peek request");
-				if (unpeekedIndex > 0) {
-					bufferPeeked[unpeekedIndex] = true;
 					return true;
 				} else {
-					return source.peek();
+					debug("Buffer fully peeked, forwarding peek to upstream");
+					return peekUpstream(source);
 				}
 			}
 		},
 		read: function produceValue_bufferedSourceStream(source) {
+			debug("Got read request");
+			
 			return Promise.try(() => {
 				if (buffer == null) {
+					debug("Waiting for upstream read...");
 					return attemptRead(source.read);
 				}
 			}).then(() => {
@@ -58,7 +97,10 @@ module.exports = function bufferStream() {
 					let value = buffer.shift();
 					bufferPeeked.shift();
 
+					debug(`Picked item from buffer, ${buffer.length} items left`);
+			
 					if (buffer.length === 0) {
+						debug(`Buffer empty, unsetting...`);
 						buffer = null;
 						bufferPeeked = null;
 					}
@@ -70,4 +112,10 @@ module.exports = function bufferStream() {
 			});
 		}
 	};
+
+	return pipe([
+		bufferStream,
+		// FIXME: Can this be made parallelism-safe without force-sequentializing?
+		sequentialize()
+	]);
 };

package.json

@@ -7,13 +7,15 @@
   "license": "WTFPL OR CC0-1.0",
   "dependencies": {
     "@joepie91/unreachable": "^1.0.0",
+    "@promistream/pipe": "^0.1.4",
     "@promistream/propagate-abort": "^0.1.2",
-    "bluebird": "^3.5.4"
+    "@promistream/sequentialize": "^0.1.0",
+    "bluebird": "^3.5.4",
+    "debug": "^4.3.1"
   },
   "devDependencies": {
     "@promistream/collect": "^0.1.0",
     "@promistream/map": "^0.1.0",
-    "@promistream/pipe": "^0.1.0",
     "@promistream/range-numbers": "^0.1.1"
   }
 }

yarn.lock

@@ -52,10 +52,19 @@
     "@validatem/required" "^0.1.1"
     bluebird "^3.5.4"
 
-"@promistream/pipe@^0.1.0":
+"@promistream/pipe@^0.1.4":
-  version "0.1.2"
+  version "0.1.4"
-  resolved "https://registry.yarnpkg.com/@promistream/pipe/-/pipe-0.1.2.tgz#3e468916247e762e5ec90a831779e24677e80e57"
+  resolved "https://registry.yarnpkg.com/@promistream/pipe/-/pipe-0.1.4.tgz#ef05fe582a33768c7eb56ad20635e1b7b48ac95b"
-  integrity sha512-J0SmZcEPZ7+If9Q3zeG6OmgfGHyiQe75iv0RMEXsUwxDQ12y4yDHkK7W09VhULAQ69JGk5j4SICk5LgBZlb60A==
+  integrity sha512-4js6lhu/aTNEMosIBFcCz8Rkxc1S2V4zzI2QvZp9HqglhL5UTuxnv5VbU2ZlPFAFVID1aJOurZ8KdiVagHfOCw==
+  dependencies:
+    "@validatem/allow-extra-properties" "^0.1.0"
+    "@validatem/anything" "^0.1.0"
+    "@validatem/array-of" "^0.1.2"
+    "@validatem/core" "^0.3.15"
+    "@validatem/error" "^1.1.0"
+    "@validatem/remove-nullish-items" "^0.1.0"
+    "@validatem/required" "^0.1.1"
+    "@validatem/wrap-error" "^0.3.0"
 
 "@promistream/propagate-abort@^0.1.2", "@promistream/propagate-abort@^0.1.6":
   version "0.1.6"
@@ -75,6 +84,16 @@
     "@promistream/end-of-stream" "^0.1.0"
     "@promistream/simple-source" "^0.1.0"
 
+"@promistream/sequentialize@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@promistream/sequentialize/-/sequentialize-0.1.0.tgz#8cab499c2518ee856fcb1e13943859ca5b77ba71"
+  integrity sha512-lm7wJmlOSmBvHq49zLfs3cghOt9kcRhLezCbuhXQUXhhiaKLCvYuyA1AGId0kiJDPX2SggrU3Ojb+TOcxPEAqw==
+  dependencies:
+    "@joepie91/unreachable" "^1.0.0"
+    "@promistream/propagate-abort" "^0.1.2"
+    bluebird "^3.5.4"
+    p-defer "^3.0.0"
+
 "@promistream/simple-sink@^0.1.0":
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/@promistream/simple-sink/-/simple-sink-0.1.1.tgz#e3808179102ffe4bc10d70d681f19c649e1f3811"
@@ -133,12 +152,27 @@
     "@validatem/virtual-property" "^0.1.0"
     default-value "^1.0.0"
 
+"@validatem/anything@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/anything/-/anything-0.1.0.tgz#09b57720476b9f7ab072c3e5d0a3d4234b721435"
+  integrity sha512-VJcygPpLw2fAhh29m2qL1AybHY7Ewl7xpvVgNIZpqUwMsSZXWSmzmbZhqE4Sr6Wy2n6FbZVzVoUFREO589SPcQ==
+
+"@validatem/array-of@^0.1.2":
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/@validatem/array-of/-/array-of-0.1.2.tgz#59c09879fb41c583e45b210e7f7c78fd7f86ac33"
+  integrity sha512-3YjrZOxxlburFfRdJyPWbNoAA7a72E3/2nPCyVGTE8lekQy9NZSyrPjntMozwE14rsnGGLWFLCgNWKu73cyhxQ==
+  dependencies:
+    "@validatem/annotate-errors" "^0.1.2"
+    "@validatem/combinator" "^0.1.0"
+    "@validatem/is-array" "^0.1.0"
+    "@validatem/validation-result" "^0.1.1"
+
 "@validatem/combinator@^0.1.0", "@validatem/combinator@^0.1.1":
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/@validatem/combinator/-/combinator-0.1.2.tgz#eab893d55f1643b9c6857eaf6ff7ed2a728e89ff"
   integrity sha512-vE8t1tNXknmN62FlN6LxQmA2c6TwVKZ+fl/Wit3H2unFdOhu7SZj2kRPGjAXdK/ARh/3svYfUBeD75pea0j1Sw==
 
-"@validatem/core@^0.3.10":
+"@validatem/core@^0.3.10", "@validatem/core@^0.3.15":
   version "0.3.15"
   resolved "https://registry.yarnpkg.com/@validatem/core/-/core-0.3.15.tgz#645a0734dbc6efa3a5c39c62c5f2d8fa773f89f3"
   integrity sha512-4nBLGzgpPrPsZ5DDXDXwL5p+GUEvpAFt6I3/YUHoah+ckYmKNh9qwmWKkFZHxJVdRrTewGFRj0FPw5fqje1yxA==
@@ -242,6 +276,13 @@
     default-value "^1.0.0"
     flatten "^1.0.3"
 
+"@validatem/is-array@^0.1.0":
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/@validatem/is-array/-/is-array-0.1.1.tgz#fbe15ca8c97c30b622a5bbeb536d341e99cfc2c5"
+  integrity sha512-XD3C+Nqfpnbb4oO//Ufodzvui7SsCIW/stxZ39dP/fyRsBHrdERinkFATH5HepegtDlWMQswm5m1XFRbQiP2oQ==
+  dependencies:
+    "@validatem/error" "^1.0.0"
+
 "@validatem/is-boolean@^0.1.1":
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/@validatem/is-boolean/-/is-boolean-0.1.1.tgz#b7fafd4143ab6d23bca597c86d8c4e0ba6f6cacf"
@@ -316,6 +357,11 @@
   dependencies:
     "@validatem/error" "^1.0.0"
 
+"@validatem/remove-nullish-items@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/remove-nullish-items/-/remove-nullish-items-0.1.0.tgz#fe1a8b64d11276b506fae2bd2c41da4985a5b5ff"
+  integrity sha512-cs4YSF47TA/gHnV5muSUUqGi5PwybP5ztu5SYnPKxQVTyubvcbrFat51nOvJ2PmUasyrIccoYMmATiviXkTi6g==
+
 "@validatem/required@^0.1.0", "@validatem/required@^0.1.1":
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/@validatem/required/-/required-0.1.1.tgz#64f4a87333fc5955511634036b7f8948ed269170"
@@ -353,6 +399,19 @@
     default-value "^1.0.0"
     split-filter-n "^1.1.2"
 
+"@validatem/wrap-error@^0.3.0":
+  version "0.3.0"
+  resolved "https://registry.yarnpkg.com/@validatem/wrap-error/-/wrap-error-0.3.0.tgz#f8d170e79b6fdd68321d82c60581ad345be7d6b9"
+  integrity sha512-km5v6F/Xm7j8W/tmCmht2BTzxMLSpBUJ5MdhJD7ABEut/fdO0tNca1u1imTnWCULCJcdDHbNtpSmDMvXFg3E7Q==
+  dependencies:
+    "@validatem/combinator" "^0.1.1"
+    "@validatem/error" "^1.0.0"
+    "@validatem/match-validation-error" "^0.1.0"
+    "@validatem/validation-result" "^0.1.2"
+    as-expression "^1.0.0"
+    default-value "^1.0.0"
+    split-filter-n "^1.1.2"
+
 "@validatem/wrap-value-as-option@^0.1.0":
   version "0.1.0"
   resolved "https://registry.yarnpkg.com/@validatem/wrap-value-as-option/-/wrap-value-as-option-0.1.0.tgz#57fa8d535f6cdf40cf8c8846ad45f4dd68f44568"
@@ -434,6 +493,13 @@ create-error@^0.3.1:
   resolved "https://registry.yarnpkg.com/create-error/-/create-error-0.3.1.tgz#69810245a629e654432bf04377360003a5351a23"
   integrity sha1-aYECRaYp5lRDK/BDdzYAA6U1GiM=
 
+debug@^4.3.1:
+  version "4.3.1"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-4.3.1.tgz#f0d229c505e0c6d8c49ac553d1b13dc183f6b2ee"
+  integrity sha512-doEwdvm4PCeK4K3RQN2ZC2BYUBaxwLARCqZmMjtF8a51J2Rb0xpVloFRnCODwqjpwnAoao4pelN8l3RJdv3gRQ==
+  dependencies:
+    ms "2.1.2"
+
 default-value@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/default-value/-/default-value-1.0.0.tgz#8c6f52a5a1193fe78fdc9f86eb71d16c9757c83a"
@@ -569,6 +635,16 @@ is.object@^1.0.0:
   resolved "https://registry.yarnpkg.com/is.object/-/is.object-1.0.0.tgz#e4f4117e9f083b35c8df5cf817ea3efb0452fdfa"
   integrity sha1-5PQRfp8IOzXI31z4F+o++wRS/fo=
 
+ms@2.1.2:
+  version "2.1.2"
+  resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.2.tgz#d09d1f357b443f493382a8eb3ccd183872ae6009"
+  integrity sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w==
+
+p-defer@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/p-defer/-/p-defer-3.0.0.tgz#d1dceb4ee9b2b604b1d94ffec83760175d4e6f83"
+  integrity sha512-ugZxsxmtTln604yeYd29EGrNhazN2lywetzpKhfmQjW/VJmhpDmWbiX+h0zL8V91R0UXkhb3KtPmyq9PZw3aYw==
+
 split-filter-n@^1.1.2:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/split-filter-n/-/split-filter-n-1.1.2.tgz#268be1ec9c4d93dfb27b030c06165ac1b6f70f66"