1 files changed, 195 insertions, 0 deletions
diff --git a/src/libnetdata/ringbuffer/ringbuffer.c b/src/libnetdata/ringbuffer/ringbuffer.c
new file mode 100644
index 000000000..b30b3c39a
--- /dev/null
+++ b/src/libnetdata/ringbuffer/ringbuffer.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+#include "ringbuffer_internal.h"
+
+rbuf_t rbuf_create(size_t size)
+{
+    rbuf_t buffer = mallocz(sizeof(struct rbuf) + size);
+    memset(buffer, 0, sizeof(struct rbuf));
+
+    buffer->data = ((char*)buffer) + sizeof(struct rbuf);
+
+    buffer->head = buffer->data;
+    buffer->tail = buffer->data;
+    buffer->size = size;
+    buffer->end = buffer->data + size;
+
+    return buffer;
+}
+
+void rbuf_free(rbuf_t buffer)
+{
+    freez(buffer);
+}
+
+void rbuf_flush(rbuf_t buffer)
+{
+    buffer->head = buffer->data;
+    buffer->tail = buffer->data;
+    buffer->size_data = 0;
+}
+
+char *rbuf_get_linear_insert_range(rbuf_t buffer, size_t *bytes)
+{
+    *bytes = 0;
+    if (buffer->head == buffer->tail && buffer->size_data)
+        return NULL;
+
+    *bytes = ((buffer->head >= buffer->tail) ? buffer->end : buffer->tail) - buffer->head;
+    return buffer->head;
+}
+
+char *rbuf_get_linear_read_range(rbuf_t buffer, size_t *bytes)
+{
+    *bytes = 0;
+    if(buffer->head == buffer->tail && !buffer->size_data)
+        return NULL;
+
+    *bytes = ((buffer->tail >= buffer->head) ? buffer->end : buffer->head) - buffer->tail;
+
+    return buffer->tail;
+}
+
+int rbuf_bump_head(rbuf_t buffer, size_t bytes)
+{
+    size_t free_bytes = rbuf_bytes_free(buffer);
+    if (bytes > free_bytes)
+        return 0;
+    int i = buffer->head - buffer->data;
+    buffer->head = &buffer->data[(i + bytes) % buffer->size];
+    buffer->size_data += bytes;
+    return 1;
+}
+
+int rbuf_bump_tail_noopt(rbuf_t buffer, size_t bytes)
+{
+    if (bytes > buffer->size_data)
+        return 0;
+    int i = buffer->tail - buffer->data;
+    buffer->tail = &buffer->data[(i + bytes) % buffer->size];
+    buffer->size_data -= bytes;
+
+    return 1;
+}
+
+int rbuf_bump_tail(rbuf_t buffer, size_t bytes)
+{
+    if(!rbuf_bump_tail_noopt(buffer, bytes))
+        return 0;
+
+    // if tail catched up with head
+    // start writing buffer from beggining
+    // this is not necessary (rbuf must work well without it)
+    // but helps to optimize big writes as rbuf_get_linear_insert_range
+    // will return bigger continuous region
+    if(buffer->tail == buffer->head) {
+        assert(buffer->size_data == 0);
+        rbuf_flush(buffer);
+    }
+
+    return 1;
+}
+
+size_t rbuf_get_capacity(rbuf_t buffer)
+{
+    return buffer->size;
+}
+
+size_t rbuf_bytes_available(rbuf_t buffer)
+{
+    return buffer->size_data;
+}
+
+size_t rbuf_bytes_free(rbuf_t buffer)
+{
+    return buffer->size - buffer->size_data;
+}
+
+size_t rbuf_push(rbuf_t buffer, const char *data, size_t len)
+{
+    size_t to_cpy;
+    char *w_ptr = rbuf_get_linear_insert_range(buffer, &to_cpy);
+    if(!to_cpy)
+        return to_cpy;
+
+    to_cpy = MIN(to_cpy, len);
+    memcpy(w_ptr, data, to_cpy);
+    rbuf_bump_head(buffer, to_cpy);
+    if(to_cpy < len)
+        to_cpy += rbuf_push(buffer, &data[to_cpy], len - to_cpy);
+    return to_cpy;
+}
+
+size_t rbuf_pop(rbuf_t buffer, char *data, size_t len)
+{
+    size_t to_cpy;
+    const char *r_ptr = rbuf_get_linear_read_range(buffer, &to_cpy);
+    if(!to_cpy)
+        return to_cpy;
+
+    to_cpy = MIN(to_cpy, len);
+    memcpy(data, r_ptr, to_cpy);
+    rbuf_bump_tail(buffer, to_cpy);
+    if(to_cpy < len)
+        to_cpy += rbuf_pop(buffer, &data[to_cpy], len - to_cpy);
+    return to_cpy;
+}
+
+static inline void rbuf_ptr_inc(rbuf_t buffer, const char **ptr)
+{
+    (*ptr)++;
+    if(*ptr >= buffer->end)
+        *ptr = buffer->data;
+}
+
+int rbuf_memcmp(rbuf_t buffer, const char *haystack, const char *needle, size_t needle_bytes)
+{
+    const char *end = needle + needle_bytes;
+
+    // as head==tail can mean 2 things here
+    if (haystack == buffer->head && buffer->size_data) {
+        if (*haystack != *needle)
+            return (*haystack - *needle);
+        rbuf_ptr_inc(buffer, &haystack);
+        needle++;
+    }
+
+    while (haystack != buffer->head && needle != end) {
+        if (*haystack != *needle)
+            return (*haystack - *needle);
+        rbuf_ptr_inc(buffer, &haystack);
+        needle++;
+    }
+    return 0;
+}
+
+int rbuf_memcmp_n(rbuf_t buffer, const char *to_cmp, size_t to_cmp_bytes)
+{
+    return rbuf_memcmp(buffer, buffer->tail, to_cmp, to_cmp_bytes);
+}
+
+char *rbuf_find_bytes(rbuf_t buffer, const char *needle, size_t needle_bytes, int *found_idx)
+{
+    const char *ptr = buffer->tail;
+    *found_idx = 0;
+
+    if (!rbuf_bytes_available(buffer))
+        return NULL;
+
+    if (buffer->head == buffer->tail && buffer->size_data) {
+        if(!rbuf_memcmp(buffer, ptr, needle, needle_bytes))
+            return (char *)ptr;
+        rbuf_ptr_inc(buffer, &ptr);
+        (*found_idx)++;
+    }
+
+    while (ptr != buffer->head)
+    {
+        if(!rbuf_memcmp(buffer, ptr, needle, needle_bytes))
+            return (char *)ptr;
+        rbuf_ptr_inc(buffer, &ptr);
+        (*found_idx)++;
+    }
+    return NULL;
+}