主从同步性能优化，主从同步性能测试。

replica_shm.c

@@ -0,0 +1,110 @@
+#include "replica_shm.h"
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+
+#define REPLICA_SHM_MAGIC 0x52504C43u /* 'RPLC' */
+#define REPLICA_SHM_VER   1
+
+static inline uint64_t align8_u64(uint64_t x) { return (x + 7u) & ~7ull; }
+
+int replica_shm_open(replica_shm_t *s, const char *name, size_t total_size, int create)
+{
+    if (!s || !name || total_size < (sizeof(replica_shm_hdr_t) + 4096)) return -EINVAL;
+    memset(s, 0, sizeof(*s));
+
+    int flags = O_RDWR;
+    if (create) flags |= O_CREAT;
+
+    int fd = shm_open(name, flags, 0666);
+    if (fd < 0) return -errno;
+
+    if (create) {
+        if (ftruncate(fd, (off_t)total_size) != 0) {
+            int e = -errno; close(fd); return e;
+        }
+    }
+
+    void *p = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    if (p == MAP_FAILED) {
+        int e = -errno; close(fd); return e;
+    }
+
+    s->fd = fd;
+    s->map_size = total_size;
+    s->hdr = (replica_shm_hdr_t *)p;
+    s->data = (uint8_t *)p + sizeof(replica_shm_hdr_t);
+
+    // 初始化头
+    if (create || s->hdr->magic != REPLICA_SHM_MAGIC) {
+        memset(s->hdr, 0, sizeof(*s->hdr));
+        s->hdr->magic = REPLICA_SHM_MAGIC;
+        s->hdr->version = REPLICA_SHM_VER;
+        s->hdr->capacity = total_size - sizeof(replica_shm_hdr_t) - sizeof(replica_rec_hdr_t);
+        s->hdr->write_off = 0;
+        s->hdr->last_seq = 0;
+    }
+
+    printf("capcity:%ld\n", s->hdr->capacity);
+
+    return 0;
+}
+
+int replica_shm_append(replica_shm_t *s, uint64_t seq, const void *buf, uint32_t len, uint32_t *out_off)
+{
+    if (!s || !s->hdr || !s->data || !buf || len == 0 || !out_off) return -EINVAL;
+
+    uint64_t cap = s->hdr->capacity;
+    uint64_t off = __atomic_load_n(&s->hdr->write_off, __ATOMIC_RELAXED);
+
+    uint64_t need = align8_u64((uint64_t)sizeof(replica_rec_hdr_t) + (uint64_t)len);
+
+    // 简化：如果尾部放不下，则写一个“wrap marker”，回到 0
+    // wrap marker: hdr.len=0, seq 保留，表示消费者遇到就跳到 0
+    if (off + need > cap) {
+        replica_rec_hdr_t wrap = { .seq = seq, .len = 0, .flags = 0, .crc32 = 0, .reserved = 0 };
+        memcpy(s->data + off, &wrap, sizeof(wrap));
+        __atomic_store_n(&s->hdr->write_off, 0, __ATOMIC_RELEASE);
+        
+        off = 0;
+        if (need > cap) return -ENOSPC;  // 单条记录太大
+    }
+
+    replica_rec_hdr_t h = {0};
+    h.seq = seq;
+    h.len = len;
+    h.flags = 0;
+    h.crc32 = 0;
+
+    // 写 header + payload
+    memcpy(s->data + off, &h, sizeof(h));
+    memcpy(s->data + off + sizeof(h), buf, len);
+
+    // 发布 write_off / last_seq（保证消费者看到 payload）
+    uint64_t new_off = off + need;
+    __atomic_store_n(&s->hdr->last_seq, seq, __ATOMIC_RELEASE);
+    __atomic_store_n(&s->hdr->write_off, new_off, __ATOMIC_RELEASE);
+
+    *out_off = (uint32_t)off;
+    return 0;
+}
+
+int replica_shm_peek(replica_shm_t *s, uint32_t off, replica_rec_hdr_t *out_hdr)
+{
+    if (!s || !s->hdr || !s->data || !out_hdr) return -EINVAL;
+    if ((uint64_t)off + sizeof(replica_rec_hdr_t) > s->hdr->capacity) return -EINVAL;
+    memcpy(out_hdr, s->data + off, sizeof(*out_hdr));
+    return 0;
+}
+
+void replica_shm_close(replica_shm_t *s)
+{
+    if (!s) return;
+    if (s->hdr && s->map_size) munmap(s->hdr, s->map_size);
+    if (s->fd > 0) close(s->fd);
+    memset(s, 0, sizeof(*s));
+}