From ce9ac3eb442ac94f78f1f67f8ba2689d4a8766e4 Mon Sep 17 00:00:00 2001
From: Cheng Shao <terrorjack@type.dance>
Date: Thu, 14 Dec 2023 02:02:35 +0000
Subject: [PATCH] base: treat all FDs as "nonblocking" on wasm
On posix platforms, when performing read/write on FDs, we check the
nonblocking flag first. For FDs without this flag (e.g. stdout), we
call fdReady() first, which in turn calls poll() to wait for I/O to be
available on that FD. This is problematic for wasm32-wasi: although
select()/poll() is supported via the poll_oneoff() wasi syscall, that
syscall is rather heavyweight and runtime behavior differs in
different wasi implementations. The issue is even worse when targeting
browsers, given there's no satisfactory way to implement async I/O as
a synchronous syscall, so existing JS polyfills for wasi often give up
and simply return ENOSYS.
Before we have a proper I/O manager that avoids poll_oneoff() for
async I/O on wasm, this patch improves the status quo a lot by merely
pretending all FDs are "nonblocking". Read/write on FDs will directly
invoke read()/write(), which are much more reliably handled in
existing wasi implementations, especially those in browsers.
Fixes #23275 and the following test cases: T7773 isEOF001 openFile009
T4808 cgrun025
Approved by CLC proposal #234:
https://github.com/haskell/core-libraries-committee/issues/234
(cherry picked from commit 2eca52b4a4c14f74a5269b7eb4643fca638d1fbe)
---
libraries/base/cbits/inputReady.c | 4 ++++
libraries/base/changelog.md | 2 ++
libraries/base/tests/IO/all.T | 5 ++---
libraries/base/tests/all.T | 5 ++---
testsuite/tests/codeGen/should_run/all.T | 2 +-
5 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/libraries/base/cbits/inputReady.c b/libraries/base/cbits/inputReady.c
index 3f636c6b287..d1c1da2e4c4 100644
--- a/libraries/base/cbits/inputReady.c
+++ b/libraries/base/cbits/inputReady.c
@@ -153,6 +153,9 @@ compute_WaitForSingleObject_timeout(bool infinite, Time remaining)
int
fdReady(int fd, bool write, int64_t msecs, bool isSock)
{
+#if defined(wasm32_HOST_ARCH)
+ return 1;
+#else
bool infinite = msecs < 0;
// if we need to track the time then record the end time in case we are
@@ -477,4 +480,5 @@ fdReady(int fd, bool write, int64_t msecs, bool isSock)
}
}
#endif
+#endif // wasm32_HOST_ARCH
}
diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md
index 7220e73f2cf..845b0b94199 100644
--- a/libraries/base/changelog.md
+++ b/libraries/base/changelog.md
@@ -10,6 +10,8 @@
* Improve documentation of various functions
* Implement primitives like `lstat` and `rmdir`, for the JS backend.
+ * Treat all FDs as "nonblocking" on wasm32 ([CLC proposal #234](https://github.com/haskell/core-libraries-committee/issues/234))
+
## 4.19.0.0 *October 2023*
* Shipped with GHC 9.8.1
diff --git a/libraries/base/tests/IO/all.T b/libraries/base/tests/IO/all.T
index 946d8ea510b..5c134201451 100644
--- a/libraries/base/tests/IO/all.T
+++ b/libraries/base/tests/IO/all.T
@@ -63,7 +63,7 @@ test('hSetBuffering004', set_stdin('hSetBuffering004.hs'), compile_and_run, ['']
test('ioeGetErrorString001', normal, compile_and_run, ['-cpp'])
test('ioeGetFileName001', normal, compile_and_run, ['-cpp'])
test('ioeGetHandle001', normal, compile_and_run, ['-cpp'])
-test('isEOF001', [extra_run_opts('</dev/null'), when(arch('wasm32'), fragile(23275))], compile_and_run, [''])
+test('isEOF001', [extra_run_opts('</dev/null')], compile_and_run, [''])
test('misc001', [extra_run_opts('misc001.hs misc001.out')], compile_and_run,
[''])
@@ -76,7 +76,7 @@ test('openFile005', js_broken(22261), compile_and_run, [''])
test('openFile006', [], compile_and_run, [''])
test('openFile007', js_broken(22261), compile_and_run, [''])
test('openFile008', [cmd_prefix('ulimit -n 1024; ')], compile_and_run, [''])
-test('openFile009', [when(arch('wasm32'), fragile(23284))], compile_and_run, [''])
+test('openFile009', [], compile_and_run, [''])
test('putStr001', normal, compile_and_run, [''])
test('readFile001', js_broken(22261), compile_and_run, [''])
@@ -155,7 +155,6 @@ test('encodingerror001', normal, compile_and_run, [''])
# Requires use of the FD interface which is not supported under WINIO
test('T4808', [when(opsys('mingw32'), skip)
- , when(arch('wasm32'), fragile(23284))
,fragile_for(16909, concurrent_ways), exit_code(1)]
, compile_and_run, [''])
test('T4895', normal, compile_and_run, [''])
diff --git a/libraries/base/tests/all.T b/libraries/base/tests/all.T
index d6c0e4126a0..90893d1096a 100644
--- a/libraries/base/tests/all.T
+++ b/libraries/base/tests/all.T
@@ -174,9 +174,8 @@ test('T7457', normal, compile_and_run, [''])
test('T7773',
[when(opsys('mingw32'), skip),
js_broken(22261),
- expect_broken_for(23272, ['ghci-opt']), # unclear
- when(arch('wasm32'),
- fragile(23275))],
+ expect_broken_for(23272, ['ghci-opt']) # unclear
+ ],
compile_and_run,
[''])
# Andreas says that T7773 will not (and should not) work on Windows
diff --git a/testsuite/tests/codeGen/should_run/all.T b/testsuite/tests/codeGen/should_run/all.T
index d2b6038d0a4..fdb8c98a8e7 100644
--- a/testsuite/tests/codeGen/should_run/all.T
+++ b/testsuite/tests/codeGen/should_run/all.T
@@ -29,7 +29,7 @@ test('cgrun021', extra_ways(['nursery_chunks']), compile_and_run, [''])
test('cgrun022', normal, compile_and_run, [''])
test('cgrun024', normal, compile_and_run, [''])
test('cgrun025',
- [ omit_ghci, extra_run_opts('cgrun025.hs < /dev/null'), exit_code(1), when(arch('wasm32'), fragile(23275))],
+ [ omit_ghci, extra_run_opts('cgrun025.hs < /dev/null'), exit_code(1) ],
compile_and_run, [''])
test('cgrun026', normal, compile_and_run, [''])
test('cgrun027', normal, compile_and_run, [''])
--
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