Project reordering and mpmc code

base.h

@@ -113,9 +113,7 @@ typedef double f64;
    ------------------------------------------------------------ */
 
 #if defined(_WIN32) || defined(_WIN64)
-
 // Memory allocation
-
 static u32 plat_get_pagesize(void) {
   SYSTEM_INFO sysinfo = {0};
   GetSystemInfo(&sysinfo);
@@ -140,43 +138,11 @@ static b32 plat_mem_release(void *ptr, u64 size) {
   return VirtualFree(ptr, size, MEM_RELEASE);
 }
 
-// Semaphores
-typedef struct plat_sem {
-  HANDLE handle;
-} plat_sem;
-
-static b32 plat_sem_init(plat_sem *s, u32 initial) {
-  s->handle = CreateSemaphore(NULL, initial, LONG_MAX, NULL);
-  return s->handle != NULL;
-}
-
-static void plat_sem_wait(plat_sem *s) {
-  WaitForSingleObject(s->handle, INFINITE);
-}
-
-// static b32 plat_sem_trywait(HANDLE sem) { // Comment to prevent warning: unused function
-//   DWORD r = WaitForSingleObject(sem, 0);
-//   return r == WAIT_OBJECT_0;
-// }
-
-static void plat_sem_post(plat_sem *s, u32 count) {
-  ReleaseSemaphore(s->handle, count, NULL);
-}
-
-// static void plat_sem_destroy(plat_sem *s) { // Comment to prevent warning: unused function
-//   if (s->handle) {
-//     CloseHandle(s->handle);
-//     s->handle = NULL;
-//   }
-// }
-
 // Sleep
 static void sleep_ms(int ms) { Sleep(ms); }
 
 #elif defined(__linux__)
-
 // Memory allocation
-
 #ifndef _DEFAULT_SOURCE
 #define _DEFAULT_SOURCE
 #endif
@@ -212,33 +178,6 @@ static b32 plat_mem_release(void *ptr, u64 size) {
   return ret == 0;
 }
 
-// Semaphores
-#include <semaphore.h>
-
-typedef struct plat_sem {
-  sem_t sem;
-} plat_sem;
-
-static b32 plat_sem_init(plat_sem *s, u32 initial) {
-  return sem_init(&s->sem, 0, initial) == 0;
-}
-
-static void plat_sem_wait(plat_sem *s) {
-  while (sem_wait(&s->sem) == -1 && errno == EINTR) {
-  }
-}
-
-// static b32 plat_sem_trywait(sem_t *sem) { return sem_trywait(sem) == 0; } // Comment to prevent warning: unused function
-
-static void plat_sem_post(plat_sem *s, u32 count) {
-  for (u32 i = 0; i < count; i++) {
-    sem_post(&s->sem);
-  }
-}
-
-// static void plat_sem_destroy(plat_sem *s) { sem_destroy(&s->sem); } // Comment to prevent warning: unused function
-
 // Sleep
 static void sleep_ms(int ms) { usleep(ms * 1000); }
-
 #endif

experiments/io_uring_test.c

@@ -0,0 +1,721 @@
+/*
+# Compile
+gcc -o io_uring_test io_uring_test.c -luring
+
+# Run
+./io_uring_test
+   */
+#include "base.h"
+#include <stdint.h>
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <liburing.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define TEST_FILE "test_io_uring.txt"
+#define BUFFER_SIZE 4096
+#define NUM_BUFFERS 4
+#define NUM_REGISTERED_FILES 8 // Maximum number of files to register
+
+// Colors for output
+#define COLOR_GREEN "\033[0;32m"
+#define COLOR_RED "\033[0;31m"
+#define COLOR_YELLOW "\033[0;33m"
+#define COLOR_BLUE "\033[0;34m"
+#define COLOR_RESET "\033[0m"
+
+// Test result tracking
+typedef struct {
+  int passed;
+  int failed;
+} TestResults;
+
+static void print_success(const char *step) {
+  printf(COLOR_GREEN "[✓] SUCCESS: %s" COLOR_RESET "\n", step);
+}
+
+static void print_failure(const char *step, const char *error) {
+  printf(COLOR_RED "[✗] FAILED: %s - %s" COLOR_RESET "\n", step, error);
+}
+
+static void print_info(const char *msg) {
+  printf(COLOR_BLUE "[i] INFO: %s" COLOR_RESET "\n", msg);
+}
+
+static void print_step(const char *step) {
+  printf(COLOR_YELLOW "\n>>> Testing: %s" COLOR_RESET "\n", step);
+}
+
+// Create a test file with known content
+static int create_test_file(const char *filename, const char *content) {
+  FILE *f = fopen(filename, "w");
+  if (!f) {
+    perror("Failed to create test file");
+    return -1;
+  }
+
+  fprintf(f, "%s", content);
+  fclose(f);
+
+  printf("  Created test file: %s\n", filename);
+  return 0;
+}
+
+// Test 1: Create io_uring instance
+static int test_io_uring_create(struct io_uring *ring, TestResults *results) {
+  print_step("io_uring creation");
+
+  int ret = io_uring_queue_init(256, ring, 0);
+  if (ret < 0) {
+    print_failure("io_uring_queue_init", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("io_uring instance created");
+  results->passed++;
+  return 0;
+}
+
+// Test 2: Register buffers
+static int test_register_buffers(struct io_uring *ring, void **buffers,
+                                 struct iovec *iovs, TestResults *results) {
+  print_step("Buffer registration");
+
+  // Allocate and prepare buffers
+  size_t total_size = BUFFER_SIZE * NUM_BUFFERS;
+  *buffers = aligned_alloc(4096, total_size); // Page-aligned for O_DIRECT
+  if (!*buffers) {
+    print_failure("Buffer allocation", strerror(errno));
+    results->failed++;
+    return -1;
+  }
+
+  // Initialize iovecs
+  for (int i = 0; i < NUM_BUFFERS; i++) {
+    iovs[i].iov_base = (char *)*buffers + (i * BUFFER_SIZE);
+    iovs[i].iov_len = BUFFER_SIZE;
+    memset(iovs[i].iov_base, 0, BUFFER_SIZE);
+  }
+
+  int ret = io_uring_register_buffers(ring, iovs, NUM_BUFFERS);
+  if (ret < 0) {
+    print_failure("io_uring_register_buffers", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Buffers registered successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 2b: Register files
+static int test_register_files(struct io_uring *ring, int *fds, int num_fds,
+                               TestResults *results) {
+  print_step("File registration");
+
+  if (num_fds == 0) {
+    print_info("No files to register");
+    results->passed++;
+    return 0;
+  }
+
+  int ret = io_uring_register_files(ring, fds, num_fds);
+  if (ret < 0) {
+    // File registration might not be supported on all kernels
+    if (ret == -EOPNOTSUPP || ret == -EINVAL) {
+      print_info("File registration not supported on this kernel, skipping");
+      results->passed++;
+      return 0;
+    }
+    print_failure("io_uring_register_files", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  printf("  Registered %d files\n", num_fds);
+  print_success("Files registered successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 3: Open file
+static int test_open_file(const char *filename, int *fd, bool use_direct,
+                          TestResults *results) {
+  print_step("File opening");
+
+  // Get file size
+  struct stat st;
+  if (stat(filename, &st) != 0) {
+    print_failure("stat", strerror(errno));
+    results->failed++;
+    return -1;
+  }
+
+  int page_size = plat_get_pagesize();
+  size_t file_size = st.st_size;
+
+  printf("  File: %s\n", filename);
+  printf("  File size: %zu bytes\n", file_size);
+  printf("  Page size: %d bytes\n", page_size);
+
+  if (file_size % page_size != 0) {
+    printf("  Extending read size from %zu to %zu bytes\n", file_size,
+           ALIGN_UP_POW2(file_size, page_size));
+  }
+
+  // Try to open with specified flags
+  int flags = O_RDONLY;
+  if (use_direct) {
+    flags |= O_DIRECT;
+  }
+
+  *fd = open(filename, flags);
+  if (*fd < 0) {
+    if (use_direct) {
+      print_info("O_DIRECT failed, trying without it");
+      *fd = open(filename, O_RDONLY);
+      if (*fd < 0) {
+        print_failure("open", strerror(errno));
+        results->failed++;
+        return -1;
+      }
+      print_info("Using buffered I/O (O_DIRECT not available)");
+    } else {
+      print_failure("open", strerror(errno));
+      results->failed++;
+      return -1;
+    }
+  } else {
+    const char *io_type = use_direct ? "O_DIRECT" : "buffered I/O";
+    printf("  File opened with %s\n", io_type);
+    print_success("File opened successfully");
+  }
+
+  results->passed++;
+  return 0;
+}
+
+// Test 4: Build and submit read operation (using registered file)
+static int test_submit_read_registered(struct io_uring *ring, int file_index,
+                                       struct iovec *iovs, int buffer_id,
+                                       uint64_t user_data, size_t file_size,
+                                       TestResults *results) {
+  print_step("Building and submitting read operation (registered file)");
+
+  u32 page_size = plat_get_pagesize();
+  size_t read_size = BUFFER_SIZE;
+
+  // For O_DIRECT, ensure read size is sector-aligned
+  if (read_size > file_size) {
+    read_size = ALIGN_UP_POW2(file_size, page_size);
+    printf("  Adjusted read size to %zu bytes for O_DIRECT alignment\n",
+           read_size);
+  }
+
+  struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+  if (!sqe) {
+    print_failure("io_uring_get_sqe", "No available SQE");
+    results->failed++;
+    return -1;
+  }
+
+  // Use fixed file descriptor
+  io_uring_prep_read_fixed(sqe, file_index, iovs[buffer_id].iov_base, read_size,
+                           0, buffer_id);
+  io_uring_sqe_set_data64(sqe, user_data);
+
+  int ret = io_uring_submit(ring);
+  if (ret < 0) {
+    print_failure("io_uring_submit", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  printf("  Using registered file index: %d\n", file_index);
+  print_success("Read operation submitted successfully (registered file)");
+  results->passed++;
+  return 0;
+}
+
+// Test 4b: Build and submit read operation (using fd directly)
+static int test_submit_read(struct io_uring *ring, int fd, struct iovec *iovs,
+                            int buffer_id, uint64_t user_data,
+                            TestResults *results) {
+  print_step("Building and submitting read operation");
+
+  // Get file size for proper alignment
+  struct stat st;
+  if (fstat(fd, &st) != 0) {
+    print_failure("fstat", strerror(errno));
+    results->failed++;
+    return -1;
+  }
+
+  u32 page_size = plat_get_pagesize();
+  size_t file_size = st.st_size;
+  size_t read_size = BUFFER_SIZE;
+
+  // For O_DIRECT, ensure read size is sector-aligned
+  if (read_size > file_size) {
+    read_size = ALIGN_UP_POW2(file_size, page_size);
+    printf("  Adjusted read size to %zu bytes for O_DIRECT alignment\n",
+           read_size);
+  }
+
+  struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+  if (!sqe) {
+    print_failure("io_uring_get_sqe", "No available SQE");
+    results->failed++;
+    return -1;
+  }
+
+  // Prepare read operation using registered buffer
+  io_uring_prep_read_fixed(sqe, fd, iovs[buffer_id].iov_base, read_size, 0,
+                           buffer_id);
+  io_uring_sqe_set_data64(sqe, user_data);
+
+  int ret = io_uring_submit(ring);
+  if (ret < 0) {
+    print_failure("io_uring_submit", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Read operation submitted successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 5: Wait for completion
+static int test_wait_completion(struct io_uring *ring,
+                                struct io_uring_cqe **cqe,
+                                TestResults *results) {
+  print_step("Waiting for completion");
+
+  int ret = io_uring_wait_cqe(ring, cqe);
+  if (ret < 0) {
+    print_failure("io_uring_wait_cqe", strerror(-ret));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Completion received");
+  results->passed++;
+  return 0;
+}
+
+// Test 6: Process completion
+static int test_process_completion(struct io_uring_cqe *cqe,
+                                   uint64_t expected_user_data,
+                                   TestResults *results) {
+  print_step("Processing completion");
+
+  uint64_t user_data = io_uring_cqe_get_data64(cqe);
+  int res = cqe->res;
+
+  printf("  Completion data:\n");
+  printf("    User data: %lu (expected: %lu)\n", user_data, expected_user_data);
+  printf("    Result: %d bytes read\n", res);
+
+  if (user_data != expected_user_data) {
+    print_failure("User data mismatch",
+                  "User data doesn't match expected value");
+    results->failed++;
+    return -1;
+  }
+
+  if (res < 0) {
+    print_failure("Read operation", strerror(-res));
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Completion processed successfully");
+  results->passed++;
+  return res; // Return number of bytes read
+}
+
+// Test 7: Verify read data
+static int test_verify_data(struct iovec *iovs, int buffer_id, int bytes_read,
+                            const char *expected_content,
+                            TestResults *results) {
+  print_step("Data verification");
+
+  char *data = (char *)iovs[buffer_id].iov_base;
+
+  printf("  Read data (first 200 chars):\n");
+  printf("  ---\n");
+  for (int i = 0; i < bytes_read && i < 200; i++) {
+    putchar(data[i]);
+  }
+  if (bytes_read > 200)
+    printf("...");
+  printf("\n  ---\n");
+
+  // Check if data is not empty
+  if (bytes_read == 0) {
+    print_failure("Data verification", "No data read");
+    results->failed++;
+    return -1;
+  }
+
+  // Check if data contains expected content
+  if (expected_content && strstr(data, expected_content) == NULL) {
+    print_failure("Data verification", "Expected content not found");
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Data verified successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 8: Test multiple concurrent reads
+static int test_concurrent_reads(struct io_uring *ring, int fd,
+                                 struct iovec *iovs, TestResults *results) {
+  print_step("Concurrent reads test");
+
+  int num_reads = 3;
+  int submitted = 0;
+
+  // Submit multiple reads
+  for (int i = 0; i < num_reads; i++) {
+    struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+    if (!sqe) {
+      print_failure("Getting SQE for concurrent read", "No available SQE");
+      results->failed++;
+      return -1;
+    }
+
+    off_t offset = i * 100; // Read from different offsets
+    io_uring_prep_read_fixed(sqe, fd, iovs[i].iov_base, BUFFER_SIZE, offset, i);
+    io_uring_sqe_set_data64(sqe, i);
+    submitted++;
+  }
+
+  int ret = io_uring_submit(ring);
+  if (ret != submitted) {
+    char msg[64];
+    snprintf(msg, sizeof(msg), "Expected %d, got %d", submitted, ret);
+
+    print_failure("Submitting concurrent reads", msg);
+    results->failed++;
+    return -1;
+  }
+
+  print_success("Concurrent reads submitted");
+
+  // Wait for and process completions
+  for (int i = 0; i < submitted; i++) {
+    struct io_uring_cqe *cqe;
+    ret = io_uring_wait_cqe(ring, &cqe);
+    if (ret < 0) {
+      print_failure("Waiting for concurrent read completion", strerror(-ret));
+      results->failed++;
+      return -1;
+    }
+
+    uint64_t user_data = io_uring_cqe_get_data64(cqe);
+    int res = cqe->res;
+
+    printf("  Concurrent read %lu completed: %d bytes read\n", user_data, res);
+    io_uring_cqe_seen(ring, cqe);
+  }
+
+  print_success("Concurrent reads completed successfully");
+  results->passed++;
+  return 0;
+}
+
+// Test 9: Test file registration with multiple files
+static int test_file_registration(struct io_uring *ring, TestResults *results) {
+  print_step("File registration with multiple files");
+
+  // Create multiple test files
+  const char *filenames[] = {"test_file1.txt", "test_file2.txt",
+                             "test_file3.txt"};
+  const char *contents[] = {"Content of file 1: Hello World!",
+                            "Content of file 2: io_uring is fast!",
+                            "Content of file 3: Registered files test."};
+
+  int fds[3];
+  int num_files = 3;
+
+  // Create and open files
+  for (int i = 0; i < num_files; i++) {
+    if (create_test_file(filenames[i], contents[i]) != 0) {
+      results->failed++;
+      return -1;
+    }
+
+    fds[i] = open(filenames[i], O_RDONLY);
+    if (fds[i] < 0) {
+      print_failure("Opening file for registration", strerror(errno));
+      // Close previously opened files
+      for (int j = 0; j < i; j++)
+        close(fds[j]);
+      results->failed++;
+      return -1;
+    }
+  }
+
+  // Register files
+  int ret = io_uring_register_files(ring, fds, num_files);
+  if (ret < 0) {
+    if (ret == -EOPNOTSUPP || ret == -EINVAL) {
+      print_info("File registration not supported, skipping test");
+      results->passed++;
+    } else {
+      print_failure("io_uring_register_files", strerror(-ret));
+      results->failed++;
+    }
+    // Cleanup
+    for (int i = 0; i < num_files; i++) {
+      close(fds[i]);
+      remove(filenames[i]);
+    }
+    return (ret == -EOPNOTSUPP || ret == -EINVAL) ? 0 : -1;
+  }
+
+  print_success("Multiple files registered successfully");
+
+  // Read from each registered file using fixed operations
+  for (int i = 0; i < num_files; i++) {
+    struct iovec iov;
+    char buf[256] = {0};
+    iov.iov_base = buf;
+    iov.iov_len = sizeof(buf);
+
+    // Register a single buffer for this test
+    ret = io_uring_register_buffers(ring, &iov, 1);
+    if (ret < 0) {
+      print_failure("Registering buffer for file test", strerror(-ret));
+      break;
+    }
+
+    struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
+    if (!sqe) {
+      print_failure("Getting SQE for registered file", "No available SQE");
+      break;
+    }
+
+    // Use fixed file and fixed buffer
+    io_uring_prep_read_fixed(sqe, i, iov.iov_base, strlen(contents[i]), 0, 0);
+    io_uring_sqe_set_data64(sqe, i);
+
+    ret = io_uring_submit(ring);
+    if (ret < 0) {
+      print_failure("Submitting read for registered file", strerror(-ret));
+      break;
+    }
+
+    struct io_uring_cqe *cqe;
+    ret = io_uring_wait_cqe(ring, &cqe);
+    if (ret < 0) {
+      print_failure("Waiting for registered file read", strerror(-ret));
+      break;
+    }
+
+    if (cqe->res < 0) {
+      print_failure("Reading registered file", strerror(-cqe->res));
+      io_uring_cqe_seen(ring, cqe);
+      break;
+    }
+
+    printf("  File %d: Read %d bytes: %.*s\n", i, cqe->res, cqe->res, buf);
+    io_uring_cqe_seen(ring, cqe);
+
+    // Unregister buffer for next iteration
+    io_uring_unregister_buffers(ring);
+  }
+
+  // Cleanup files
+  io_uring_unregister_files(ring);
+  for (int i = 0; i < num_files; i++) {
+    close(fds[i]);
+    remove(filenames[i]);
+  }
+
+  print_success("File registration test completed");
+  results->passed++;
+  return 0;
+}
+
+// Cleanup function
+static void cleanup(struct io_uring *ring, int *fds, int num_fds,
+                    void *buffers) {
+  if (fds) {
+    io_uring_unregister_files(ring);
+    for (int i = 0; i < num_fds; i++) {
+      if (fds[i] >= 0)
+        close(fds[i]);
+    }
+  }
+  if (buffers) {
+    io_uring_unregister_buffers(ring);
+    free(buffers);
+  }
+  io_uring_queue_exit(ring);
+  remove(TEST_FILE);
+}
+
+int main() {
+  TestResults results = {0, 0};
+  struct io_uring ring;
+  int fd = -1;
+  int registered_fds[1] = {-1}; // For registered file test
+  void *buffers = NULL;
+  struct iovec iovs[NUM_BUFFERS];
+
+  printf(COLOR_BLUE "\n========================================\n");
+  printf("    io_uring Test Suite with File Registration\n");
+  printf("========================================\n" COLOR_RESET);
+
+  // Create main test file
+  const char *test_content =
+      "Hello, io_uring! This is a test file for async I/O operations.\n"
+      "Line 2: Testing reads with registered buffers.\n"
+      "Line 3: The quick brown fox jumps over the lazy dog.\n"
+      "Line 4: ABCDEFGHIJKLMNOPQRSTUVWXYZ\n"
+      "Line 5: 0123456789\n";
+
+  if (create_test_file(TEST_FILE, test_content) != 0) {
+    return 1;
+  }
+
+  // Test 1: Create io_uring
+  if (test_io_uring_create(&ring, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 2: Register buffers
+  if (test_register_buffers(&ring, &buffers, iovs, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 3: Open file
+  if (test_open_file(TEST_FILE, &fd, true, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 4: Submit read with direct fd
+  uint64_t test_user_data = 12345;
+  if (test_submit_read(&ring, fd, iovs, 0, test_user_data, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 5: Wait for completion
+  struct io_uring_cqe *cqe;
+  if (test_wait_completion(&ring, &cqe, &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 6: Process completion
+  int bytes_read = test_process_completion(cqe, test_user_data, &results);
+  if (bytes_read < 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+  io_uring_cqe_seen(&ring, cqe);
+
+  // Test 7: Verify data
+  if (test_verify_data(iovs, 0, bytes_read, "io_uring", &results) != 0) {
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Close the file for file registration test
+  close(fd);
+
+  // Reopen and register the file
+  registered_fds[0] = open(TEST_FILE, O_RDONLY);
+  if (registered_fds[0] < 0) {
+    print_failure("Reopening file for registration", strerror(errno));
+    cleanup(&ring, NULL, 0, buffers);
+    return 1;
+  }
+
+  // Test 2b: Register files
+  if (test_register_files(&ring, registered_fds, 1, &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Get file size for the registered read test
+  struct stat st;
+  stat(TEST_FILE, &st);
+
+  // Test 4b: Submit read using registered file
+  test_user_data = 67890;
+  if (test_submit_read_registered(&ring, 0, iovs, 0, test_user_data, st.st_size,
+                                  &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Wait for and process completion
+  if (test_wait_completion(&ring, &cqe, &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  bytes_read = test_process_completion(cqe, test_user_data, &results);
+  if (bytes_read < 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+  io_uring_cqe_seen(&ring, cqe);
+
+  // Verify data from registered file read
+  if (test_verify_data(iovs, 0, bytes_read, "io_uring", &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Test 8: Concurrent reads
+  if (test_concurrent_reads(&ring, registered_fds[0], iovs, &results) != 0) {
+    cleanup(&ring, registered_fds, 1, buffers);
+    return 1;
+  }
+
+  // Test 9: File registration with multiple files (requires new ring)
+  cleanup(&ring, registered_fds, 1, buffers);
+  buffers = NULL;
+  registered_fds[0] = -1;
+
+  if (test_io_uring_create(&ring, &results) != 0) {
+    return 1;
+  }
+
+  test_file_registration(&ring, &results);
+
+  // Cleanup the second ring
+  io_uring_queue_exit(&ring);
+
+  // Print summary
+  printf(COLOR_BLUE "\n========================================\n");
+  printf("           TEST SUMMARY\n");
+  printf("========================================\n" COLOR_RESET);
+  printf("  Total tests: %d\n", results.passed + results.failed);
+  printf(COLOR_GREEN "  Passed: %d\n" COLOR_RESET, results.passed);
+  if (results.failed > 0) {
+    printf(COLOR_RED "  Failed: %d\n" COLOR_RESET, results.failed);
+  } else {
+    printf(COLOR_GREEN "  ✓ ALL TESTS PASSED!\n" COLOR_RESET);
+  }
+
+  return results.failed > 0 ? 1 : 0;
+}

experiments/io_uring_test2.c

@@ -1,6 +1,6 @@
 /*
 # Compile
-gcc -o io_uring_test io_uring_test.c -luring
+gcc -o io_uring_test io_uring_test2.c -luring
 
 # Run
 ./io_uring_test

lf_mpmc.h

@@ -2,6 +2,7 @@
 
 #include "base.h"
 
+// Cache align abstraction
 #define CACHELINE 64
 
 #if defined(_MSC_VER)
@@ -10,6 +11,7 @@
 #define CACHE_ALIGN __attribute__((aligned(CACHELINE)))
 #endif
 
+// Compiler hints
 #if defined(__GNUC__) || defined(__clang__)
 #define likely(x) __builtin_expect((x), 1)
 #define unlikely(x) __builtin_expect((x), 0)
@@ -24,6 +26,65 @@ static void cpu_pause(void) {
 #endif
 }
 
+// Semaphores
+#if defined(_WIN32) || defined(_WIN64)
+typedef struct plat_sem {
+  HANDLE handle;
+} plat_sem;
+
+static b32 plat_sem_init(plat_sem *s, u32 initial) {
+  s->handle = CreateSemaphore(NULL, initial, LONG_MAX, NULL);
+  return s->handle != NULL;
+}
+
+static void plat_sem_wait(plat_sem *s) {
+  WaitForSingleObject(s->handle, INFINITE);
+}
+
+// static b32 plat_sem_trywait(HANDLE sem) { // Comment to prevent warning: unused function
+//   DWORD r = WaitForSingleObject(sem, 0);
+//   return r == WAIT_OBJECT_0;
+// }
+
+static void plat_sem_post(plat_sem *s, u32 count) {
+  ReleaseSemaphore(s->handle, count, NULL);
+}
+
+// static void plat_sem_destroy(plat_sem *s) { // Comment to prevent warning: unused function
+//   if (s->handle) {
+//     CloseHandle(s->handle);
+//     s->handle = NULL;
+//   }
+// }
+
+#elif defined(__linux__)
+#include <semaphore.h>
+
+typedef struct plat_sem {
+  sem_t sem;
+} plat_sem;
+
+static b32 plat_sem_init(plat_sem *s, u32 initial) {
+  return sem_init(&s->sem, 0, initial) == 0;
+}
+
+static void plat_sem_wait(plat_sem *s) {
+  while (sem_wait(&s->sem) == -1 && errno == EINTR) {
+  }
+}
+
+// static b32 plat_sem_trywait(sem_t *sem) { return sem_trywait(sem) == 0; } // Comment to prevent warning: unused function
+
+static void plat_sem_post(plat_sem *s, u32 count) {
+  for (u32 i = 0; i < count; i++) {
+    sem_post(&s->sem);
+  }
+}
+
+// static void plat_sem_destroy(plat_sem *s) { sem_destroy(&s->sem); } // Comment to prevent warning: unused function
+
+#endif
+
 typedef struct plat_sem plat_sem;
 
 typedef struct CACHE_ALIGN {
@@ -235,6 +296,7 @@ static void mpmc_push_work(MPMCQueue *q, void *item) {
   atomic_fetch_add(&q->work_count, 1);
   plat_sem_post(&q->items_sem, 1);
 }
+
 /* ----------------------------------------------------------- */
 /* POP */
 /* ----------------------------------------------------------- */

mt_mpmc.h

@@ -0,0 +1,246 @@
+#pragma once 
+
+#include "base.h"
+
+// Cache align abstraction
+#define CACHELINE 64
+
+#if defined(_MSC_VER)
+#define CACHE_ALIGN __declspec(align(CACHELINE))
+#else
+#define CACHE_ALIGN __attribute__((aligned(CACHELINE)))
+#endif
+
+// Mutex/Critical section abstraction
+#if defined(_WIN32)
+#include <windows.h>
+typedef CRITICAL_SECTION mtx_t;
+typedef CONDITION_VARIABLE cond_t;
+
+#define mtx_init(m) InitializeCriticalSection(m)
+#define mtx_lock(m) EnterCriticalSection(m)
+#define mtx_unlock(m) LeaveCriticalSection(m)
+#define mtx_destroy(m) DeleteCriticalSection(m)
+
+#define cond_init(c) InitializeConditionVariable(c)
+#define cond_wait(c, m) SleepConditionVariableCS(c, m, INFINITE)
+#define cond_signal(c) WakeConditionVariable(c)
+#define cond_broadcast(c) WakeAllConditionVariable(c)
+
+#else
+#include <pthread.h>
+typedef pthread_mutex_t mtx_t;
+typedef pthread_cond_t cond_t;
+
+#define mtx_init(m) pthread_mutex_init(m, NULL)
+#define mtx_lock(m) pthread_mutex_lock(m)
+#define mtx_unlock(m) pthread_mutex_unlock(m)
+#define mtx_destroy(m) pthread_mutex_destroy(m)
+
+#define cond_init(c) pthread_cond_init(c, NULL)
+#define cond_wait(c, m) pthread_cond_wait(c, m)
+#define cond_signal(c) pthread_cond_signal(c)
+#define cond_broadcast(c) pthread_cond_broadcast(c)
+
+#endif
+
+typedef struct CACHE_ALIGN {
+  void *data;
+  char pad[64 - sizeof(void *)];
+} MPMCSlot;
+
+typedef struct {
+  CACHE_ALIGN size_t head;
+  CACHE_ALIGN size_t tail;
+
+  CACHE_ALIGN size_t count;
+  CACHE_ALIGN size_t work_count;
+
+  size_t capacity;
+  size_t mask;
+
+  size_t committed;
+  size_t commit_step;
+
+  mtx_t lock;
+  cond_t not_empty;
+  cond_t not_full;
+
+  MPMCSlot *slots;
+} MPMCQueue;
+
+/* ----------------------------------------------------------- */
+/* INIT */
+/* ----------------------------------------------------------- */
+static void mpmc_init(MPMCQueue *q, size_t max_capacity) {
+  q->capacity = max_capacity;
+  q->mask = max_capacity - 1;
+
+  size_t pagesize = plat_get_pagesize();
+  size_t bytes = ALIGN_UP_POW2(sizeof(MPMCSlot) * max_capacity, pagesize);
+
+  q->slots = (MPMCSlot *)plat_mem_reserve(bytes);
+  if (!q->slots) {
+    fprintf(stderr, "plat_mem_reserve failed\n");
+    exit(1);
+  }
+
+  size_t commit_bytes = ALIGN_UP_POW2(pagesize, pagesize);
+  q->commit_step = commit_bytes / sizeof(MPMCSlot);
+
+  q->committed = q->commit_step;
+  plat_mem_commit(q->slots, commit_bytes);
+
+  for (size_t i = 0; i < q->committed; i++) {
+    q->slots[i].data = NULL;
+  }
+
+  q->head = 0;
+  q->tail = 0;
+  q->count = 0;
+  q->work_count = 0;
+
+  mtx_init(&q->lock);
+  cond_init(&q->not_empty);
+  cond_init(&q->not_full);
+}
+
+/* ----------------------------------------------------------- */
+/* COMMIT MORE MEMORY */
+/* ----------------------------------------------------------- */
+static void mpmc_commit_more(MPMCQueue *q) {
+  size_t start = q->committed;
+
+  if (start >= q->capacity)
+    return;
+
+  size_t new_commit = start + q->commit_step;
+  if (new_commit > q->capacity)
+    new_commit = q->capacity;
+
+  size_t count = new_commit - start;
+
+  plat_mem_commit(&q->slots[start], count * sizeof(MPMCSlot));
+
+  for (size_t i = start; i < new_commit; i++) {
+    q->slots[i].data = NULL;
+  }
+
+  q->committed = new_commit;
+}
+
+/* ----------------------------------------------------------- */
+/* PUSH */
+/* ----------------------------------------------------------- */
+// Does not increment work
+static void mpmc_push(MPMCQueue *q, void *item) {
+  mtx_lock(&q->lock);
+
+  while (q->count == q->capacity) {
+    cond_wait(&q->not_full, &q->lock);
+  }
+
+  // Ensure committed
+  if (q->tail >= q->committed) {
+    mpmc_commit_more(q);
+  }
+
+  size_t pos = q->tail & q->mask;
+
+  q->slots[pos].data = item;
+  q->tail++;
+  q->count++;
+
+  cond_signal(&q->not_empty);
+  mtx_unlock(&q->lock);
+}
+
+// Increment work
+static void mpmc_push_work(MPMCQueue *q, void *item) {
+  mtx_lock(&q->lock);
+
+  while (q->count == q->capacity) {
+    cond_wait(&q->not_full, &q->lock);
+  }
+
+  if (q->tail >= q->committed) {
+    mpmc_commit_more(q);
+  }
+
+  size_t pos = q->tail & q->mask;
+
+  q->slots[pos].data = item;
+  q->tail++;
+  q->count++;
+  q->work_count++;
+
+  cond_signal(&q->not_empty);
+  mtx_unlock(&q->lock);
+}
+
+/* ----------------------------------------------------------- */
+/* POP */
+/* ----------------------------------------------------------- */
+static void *mpmc_pop(MPMCQueue *q) {
+  mtx_lock(&q->lock);
+
+  while (q->count == 0) {
+    cond_wait(&q->not_empty, &q->lock);
+  }
+
+  size_t pos = q->head & q->mask;
+
+  void *data = q->slots[pos].data;
+
+  q->head++;
+  q->count--;
+
+  cond_signal(&q->not_full);
+  mtx_unlock(&q->lock);
+
+  return data;
+}
+
+/* ----------------------------------------------------------- */
+/* PUSH POISON */
+/* ----------------------------------------------------------- */
+static void mpmc_producers_finished(MPMCQueue *q, u8 consumer_count) {
+  for (u8 i = 0; i < consumer_count; i++) {
+    mpmc_push(q, NULL);
+  }
+}
+
+/* ----------------------------------------------------------- */
+/* Done */
+/* ----------------------------------------------------------- */
+static void mpmc_task_done(MPMCQueue *q, u8 consumer_count) {
+  mtx_lock(&q->lock);
+
+  if (--q->work_count == 0) {
+     mpmc_producers_finished(q, consumer_count);
+  }
+
+  mtx_unlock(&q->lock);
+}
+
+/* ----------------------------------------------------------- */
+/* MPMC Cleanup */
+/* ----------------------------------------------------------- */
+// static void mpmc_finish(MPMCQueue *q) { // Comment to prevent warning: unused function
+//   if (!q) return;
+//
+//   if (q->slots) {
+//     plat_mem_release(q->slots, 0);
+//     q->slots = NULL;
+//   }
+//
+//   mtx_destroy(&q->lock);
+//
+// #if !defined(_WIN32)
+//   pthread_cond_destroy(&q->not_empty);
+//   pthread_cond_destroy(&q->not_full);
+// #endif
+//
+//   q->capacity = 0;
+//   q->mask = 0;
+// }

platform.c

@@ -1,5 +1,5 @@
-#pragma once // ensure that a given header file is included only once in a
+#pragma once 
-             // single compilation unit
+
 #include "arena.h"
 #include "base.h"
 #include "lf_mpmc.h"
@@ -1296,10 +1296,10 @@ static BUILD_READ_RETURN_VALUE ioring_build_read(ThreadIoContext *thread_ctx,
 }
 
 static void ioring_process_completions(ThreadIoContext *thread_ctx) {
-  uint32_t waited = 0;
+  uint32_t cqe_count = 0;
-  uint32_t target = MIN(thread_ctx->num_submissions, MAX_WAIT_COUNT);
+  uint32_t wait_count = MIN(thread_ctx->num_submissions, MAX_WAIT_COUNT);
 
-  while (waited < target) {
+  while (cqe_count < wait_count) {
 
     // ---- Drain all available CQEs (non-blocking) ----
     while (1) {
@@ -1307,7 +1307,7 @@ static void ioring_process_completions(ThreadIoContext *thread_ctx) {
 
       HRESULT hr = PopIoRingCompletion(thread_ctx->ring, &win_cqe);
 
-      if (hr == S_FALSE) {
+      if (hr != S_OK) {
         // No more CQEs available right now
         break;
       }
@@ -1347,12 +1347,11 @@ static void ioring_process_completions(ThreadIoContext *thread_ctx) {
       file->reads_completed++;
       thread_ctx->num_submissions--;
 
-      // Count only "real" completions toward wait budget
+      cqe_count++;
-      waited++;
     }
 
     // ---- If we already waited enough, exit ----
-    if (waited >= target) {
+    if (cqe_count >= wait_count) {
       break;
     }
 
@@ -1575,18 +1574,16 @@ static int ioring_submit(ThreadIoContext *thread_ctx, uint32_t *submitted) {
 }
 
 static void ioring_process_completions(ThreadIoContext *thread_ctx) {
-  IoUring *impl = (IoUring *)thread_ctx->ring;
-
   struct io_uring_cqe *cqes[NUM_BUFFERS_PER_THREAD];
 
-  unsigned count =
+  unsigned cqe_count = io_uring_peek_batch_cqe(&((IoUring *)thread_ctx->ring)->ring,
-      io_uring_peek_batch_cqe(&impl->ring, cqes, NUM_BUFFERS_PER_THREAD);
+                                           cqes, NUM_BUFFERS_PER_THREAD);
 
-  if (count == 0) {
+  if (cqe_count == 0) {
     return;
   }
 
-  for (unsigned i = 0; i < count; i++) {
+  for (unsigned i = 0; i < cqe_count; i++) {
     struct io_uring_cqe *cqe = cqes[i];
 
     int res = cqe->res;
@@ -1613,7 +1610,7 @@ static void ioring_process_completions(ThreadIoContext *thread_ctx) {
   }
 
   // Mark CQE as seen, equivalent to io_uring_cqe_seen() but marks multiple CQEs
-  io_uring_cq_advance(&impl->ring, count);
+  io_uring_cq_advance(&((IoUring *)thread_ctx->ring)->ring, cqe_count);
 }
 
 FileHandle ioring_open_file(FileEntry *fe) {