Refactor import hook API to subsume all platform-dependent behavior

[valadaptive]

First off, apologies for leaving you hanging for a year! Some stuff came up and this fell off my radar for a while, and this seemed like it was going to be more fiddly and difficult than it ended up being.

This import hook API isolates all platform-specific path resolution stuff within the import hook itself. The hook now takes the path of the imported file and the path of the file that imported it, and calls the callback with the file contents, and the resolved path of the imported file. That second part is what stumped me on my last attempt.

I also started work last year on a "de-Buffer-ification" branch, but ran into some performance cliffs. I finally figured those out (except for TextEncoder/TextDecoder, which is still slower in Node sadly), and the code is now on GitHub. It's actually faster on most benchmarks than the Buffer version. It's still a proof-of-concept and will need to be cleaned up. If you're interested in merging it before the major version bump, maybe remove services first, so I don't have to port that over to use Uint8Array.

[mtth]

No worries and thanks for the PR @valadaptive! This change looks good overall, will send a review shortly.

Great to hear about the Uint8Array-related changes. I would probably release those with the upcoming major version. Could you share performance numbers?

[valadaptive]

I've addressed the review feedback.

Here are the perf numbers for the Uint8Array change:

Perf tables

With Buffer:

fromBuffer	toBuffer	isValid	(ops/sec)
33,317,478	10,631,527	180,366,905	ArrayInt.avsc
3,468,574	2,534,513	128,928,596	ArrayString.avsc
7,582,504	8,709,989	197,814,804	Bytes.avsc
689,280	679,409	2,674,241	Cake.avsc
2,592,217	2,206,942	38,822,853	Coupon.avsc
57,056,424	12,550,699	113,024,376	Double.avsc
61,574,774	11,820,736	60,649,981	Enum.avsc
61,538,321	13,354,808	114,390,373	Float.avsc
2,589,185	2,428,255	5,927,018	HistoryItem.avsc
3,151,044	3,205,620	53,984,621	Human.avsc
77,905,322	13,794,184	112,848,911	Int.avsc
34,027,942	12,880,509	104,609,630	Long.avsc
293,783	378,512	939,211	PciEvent.avsc
27,126,506	8,379,302	30,641,460	Person.avsc
9,307,901	5,816,258	57,643,068	ProtobufTest.avsc
12,765,398	8,389,290	102,736,271	String.avsc
195,432	113,200	1,012,104	Tile.avsc
18,685,374	7,854,798	35,397,755	Union.avsc
1,480,839	1,066,944	4,599,581	User.avsc

With Uint8Array + Buffer functions for string encoding / decoding:

fromBuffer	toBuffer	isValid	(ops/sec)
26,724,848	17,414,862	173,377,550	ArrayInt.avsc
3,818,504	2,697,317	90,991,170	ArrayString.avsc
21,207,217	9,736,062	166,809,986	Bytes.avsc
843,434	642,307	2,612,795	Cake.avsc
3,314,544	2,131,250	37,131,186	Coupon.avsc
79,127,110	25,606,001	233,078,420	Double.avsc
79,373,943	21,588,047	79,517,556	Enum.avsc
106,002,679	26,058,862	233,474,594	Float.avsc
3,487,554	2,564,875	6,504,066	HistoryItem.avsc
5,214,008	3,056,836	49,537,779	Human.avsc
98,066,155	25,794,709	221,886,611	Int.avsc
37,888,878	21,836,901	193,645,566	Long.avsc
387,944	325,432	919,929	PciEvent.avsc
28,923,151	14,010,220	31,192,161	Person.avsc
10,576,640	7,687,052	83,377,019	ProtobufTest.avsc
15,767,017	11,890,621	210,533,610	String.avsc
209,431	117,867	956,955	Tile.avsc
21,418,426	11,937,821	36,588,398	Union.avsc
1,545,082	1,177,994	4,776,210	User.avsc

With Uint8Array + TextEncoder and TextDecoder:

fromBuffer	toBuffer	isValid	(ops/sec)
30,183,380	17,957,895	172,694,579	ArrayInt.avsc
3,125,114	2,268,559	83,375,656	ArrayString.avsc
23,428,938	8,569,906	164,245,978	Bytes.avsc
825,634	716,936	2,630,647	Cake.avsc
3,522,090	1,849,812	45,443,725	Coupon.avsc
79,602,728	24,994,036	231,514,849	Double.avsc
77,108,732	21,662,621	95,794,477	Enum.avsc
106,725,988	26,097,755	230,470,649	Float.avsc
2,722,699	2,289,792	6,548,083	HistoryItem.avsc
5,321,199	2,920,507	70,267,637	Human.avsc
99,272,048	25,639,119	225,582,362	Int.avsc
37,210,513	21,793,239	195,846,122	Long.avsc
507,922	495,641	1,422,177	PciEvent.avsc
26,569,325	14,217,492	36,755,572	Person.avsc
10,310,916	9,077,304	91,752,339	ProtobufTest.avsc
14,347,258	12,477,982	210,278,354	String.avsc
232,691	119,787	944,537	Tile.avsc
18,955,988	11,204,323	45,527,142	Union.avsc
1,489,976	1,047,133	4,866,507	User.avsc

Not sure what the ArrayInt result is about (in previous tests, they've been about equivalent) but everything else seems way faster.

[mtth]

Thanks @valadaptive. The numbers above look great. Did you mean to push changes to this branch?

[valadaptive]

Yup, my bad! Changes have been properly pushed now.

[mtth]

Apologies for the slow review.

[mtth]

Thanks for updating. Looks good - just two minor changes and this should be ready to merge.

[valadaptive]

I've made those last few changes and also stopped exporting existsSync and readFileSync now that that functionality's been moved into files.js.

[mtth]

Thanks @valadaptive!