X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=io_uring_engine.cpp;h=fc51abab6a75e23143235f555e8edec82547529b;hb=8c40d71acb262d9efe84af89e28a448bddadbabe;hp=fb0a4de443d25ec99ff13ff6c1b11ca6a5897962;hpb=94cd9258309ac4316632b0376cb92b04397e789f;p=plocate

diff --git a/io_uring_engine.cpp b/io_uring_engine.cpp
index fb0a4de..fc51aba 100644
--- a/io_uring_engine.cpp
+++ b/io_uring_engine.cpp
@@ -1,3 +1,6 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #ifndef WITHOUT_URING
 #include <liburing.h>
@@ -5,13 +8,15 @@
 #include "io_uring_engine.h"
 
 #include <functional>
-#include <memory>
-#include <stdint.h>
+#include <iosfwd>
+#include <string>
 #include <unistd.h>
+#include <utility>
 
 using namespace std;
 
-IOUringEngine::IOUringEngine()
+IOUringEngine::IOUringEngine(size_t slop_bytes)
+	: slop_bytes(slop_bytes)
 {
 #ifdef WITHOUT_URING
 	int ret = -1;
@@ -21,14 +26,14 @@ IOUringEngine::IOUringEngine()
 	using_uring = (ret >= 0);
 }
 
-void IOUringEngine::submit_read(int fd, size_t len, off_t offset, function<void(string)> cb)
+void IOUringEngine::submit_read(int fd, size_t len, off_t offset, function<void(string_view)> cb)
 {
 	if (!using_uring) {
 		// Synchronous read.
 		string s;
-		s.resize(len);
+		s.resize(len + slop_bytes);
 		complete_pread(fd, &s[0], len, offset);
-		cb(move(s));
+		cb(string_view(s.data(), len));
 		return;
 	}
 
@@ -47,10 +52,10 @@ void IOUringEngine::submit_read(int fd, size_t len, off_t offset, function<void(
 }
 
 #ifndef WITHOUT_URING
-void IOUringEngine::submit_read_internal(io_uring_sqe *sqe, int fd, size_t len, off_t offset, function<void(string)> cb)
+void IOUringEngine::submit_read_internal(io_uring_sqe *sqe, int fd, size_t len, off_t offset, function<void(string_view)> cb)
 {
 	void *buf;
-	if (posix_memalign(&buf, /*alignment=*/4096, len)) {
+	if (posix_memalign(&buf, /*alignment=*/4096, len + slop_bytes)) {
 		fprintf(stderr, "Couldn't allocate %zu bytes: %s\n", len, strerror(errno));
 		exit(1);
 	}
@@ -69,54 +74,65 @@ void IOUringEngine::finish()
 	}
 
 #ifndef WITHOUT_URING
-	int ret = io_uring_submit(&ring);
-	if (ret < 0) {
-		fprintf(stderr, "io_uring_submit: %s\n", strerror(-ret));
-		exit(1);
-	}
-	bool anything_to_submit = false;
+	bool anything_to_submit = true;
 	while (pending_reads > 0) {
 		io_uring_cqe *cqe;
-		ret = io_uring_wait_cqe(&ring, &cqe);
-		if (ret < 0) {
-			fprintf(stderr, "io_uring_wait_cqe: %s\n", strerror(-ret));
-			exit(1);
-		}
-
-		PendingRead *pending = reinterpret_cast<PendingRead *>(cqe->user_data);
-		if (cqe->res <= 0) {
-			fprintf(stderr, "async read failed: %s\n", strerror(-cqe->res));
-			exit(1);
+		if (io_uring_peek_cqe(&ring, &cqe) != 0) {
+			if (anything_to_submit) {
+				// Nothing ready, so submit whatever is pending and then do a blocking wait.
+				int ret = io_uring_submit_and_wait(&ring, 1);
+				if (ret < 0) {
+					fprintf(stderr, "io_uring_submit(queued): %s\n", strerror(-ret));
+					exit(1);
+				}
+				anything_to_submit = false;
+			} else {
+				int ret = io_uring_wait_cqe(&ring, &cqe);
+				if (ret < 0) {
+					fprintf(stderr, "io_uring_wait_cqe: %s\n", strerror(-ret));
+					exit(1);
+				}
+			}
 		}
 
-		if (size_t(cqe->res) < pending->iov.iov_len) {
-			// Incomplete read, so resubmit it.
-			pending->iov.iov_base = (char *)pending->iov.iov_base + cqe->res;
-			pending->iov.iov_len -= cqe->res;
-			pending->offset += cqe->res;
-			io_uring_cqe_seen(&ring, cqe);
-
-			io_uring_sqe *sqe = io_uring_get_sqe(&ring);
-			if (sqe == nullptr) {
-				fprintf(stderr, "No free SQE for resubmit; this shouldn't happen.\n");
+		unsigned head;
+		io_uring_for_each_cqe(&ring, head, cqe)
+		{
+			PendingRead *pending = reinterpret_cast<PendingRead *>(cqe->user_data);
+			if (cqe->res <= 0) {
+				fprintf(stderr, "async read failed: %s\n", strerror(-cqe->res));
 				exit(1);
 			}
-			io_uring_prep_readv(sqe, pending->fd, &pending->iov, 1, pending->offset);
-			io_uring_sqe_set_data(sqe, pending);
-			anything_to_submit = true;
-		} else {
-			io_uring_cqe_seen(&ring, cqe);
-			--pending_reads;
-
-			size_t old_pending_reads = pending_reads;
-			pending->cb(string(reinterpret_cast<char *>(pending->buf), pending->len));
-			free(pending->buf);
-			delete pending;
-
-			if (pending_reads != old_pending_reads) {
-				// A new read was made in the callback (and not queued),
-				// so we need to re-submit.
+
+			if (size_t(cqe->res) < pending->iov.iov_len) {
+				// Incomplete read, so resubmit it.
+				pending->iov.iov_base = (char *)pending->iov.iov_base + cqe->res;
+				pending->iov.iov_len -= cqe->res;
+				pending->offset += cqe->res;
+				io_uring_cqe_seen(&ring, cqe);
+
+				io_uring_sqe *sqe = io_uring_get_sqe(&ring);
+				if (sqe == nullptr) {
+					fprintf(stderr, "No free SQE for resubmit; this shouldn't happen.\n");
+					exit(1);
+				}
+				io_uring_prep_readv(sqe, pending->fd, &pending->iov, 1, pending->offset);
+				io_uring_sqe_set_data(sqe, pending);
 				anything_to_submit = true;
+			} else {
+				io_uring_cqe_seen(&ring, cqe);
+				--pending_reads;
+
+				size_t old_pending_reads = pending_reads;
+				pending->cb(string_view(reinterpret_cast<char *>(pending->buf), pending->len));
+				free(pending->buf);
+				delete pending;
+
+				if (pending_reads != old_pending_reads) {
+					// A new read was made in the callback (and not queued),
+					// so we need to re-submit.
+					anything_to_submit = true;
+				}
 			}
 		}
 
@@ -132,17 +148,6 @@ void IOUringEngine::finish()
 			queued_reads.pop();
 			anything_to_submit = true;
 		}
-
-		if (anything_to_submit) {
-			// A new read was made, so we need to re-submit.
-			int ret = io_uring_submit(&ring);
-			if (ret < 0) {
-				fprintf(stderr, "io_uring_submit(queued): %s\n", strerror(-ret));
-				exit(1);
-			} else {
-				anything_to_submit = false;
-			}
-		}
 	}
 #endif
 }