--- /dev/null
+/*
+ * experimental weighted round robin scheduler - (c) 2007 willy tarreau.
+ *
+ * This filling algorithm is excellent at spreading the servers, as it also
+ * takes care of keeping the most uniform distance between occurences of each
+ * server, by maximizing this distance. It reduces the number of variables
+ * and expensive operations.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "eb32tree.h"
+
+struct srv {
+ struct eb32_node node;
+ struct eb_root *tree; // we want to know where the server is
+ int num;
+ int w; /* weight */
+ int next, last;
+ int rem;
+} *srv;
+
+/* those trees represent a sliding window of 3 time frames */
+struct eb_root tree_0 = EB_ROOT;
+struct eb_root tree_1 = EB_ROOT;
+struct eb_root tree_2 = EB_ROOT;
+
+struct eb_root *init_tree; /* receives positions 0..sw-1 */
+struct eb_root *next_tree; /* receives positions >= 2sw */
+
+int nsrv; /* # of servers */
+int nsw, sw; /* sum of weights */
+int p; /* current position, between sw..2sw-1 */
+
+/* queue a server in the weights tree */
+void queue_by_weight(struct eb_root *root, struct srv *s) {
+ s->node.key = 255 - s->w;
+ eb32i_insert(root, &s->node);
+ s->tree = root;
+}
+
+/* queue a server in the weight tree <root>, except if its weight is 0 */
+void queue_by_weight_0(struct eb_root *root, struct srv *s) {
+ if (s->w) {
+ s->node.key = 255 - s->w;
+ eb32i_insert(root, &s->node);
+ s->tree = root;
+ } else {
+ s->tree = NULL;
+ }
+}
+
+static inline void dequeue_srv(struct srv *s) {
+ eb32_delete(&s->node);
+}
+
+/* queues a server into the correct tree depending on ->next */
+void put_srv(struct srv *s) {
+ if (s->w <= 0 ||
+ s->next >= 2*sw || /* delay everything which does not fit into the window */
+ s->next >= sw+nsw) { /* and everything which does not fit into the theorical new window */
+ /* put into next tree */
+ s->next -= sw; // readjust next in case we could finally take this back to current.
+ queue_by_weight_0(next_tree, s);
+ } else { /* FIXME: sw can be smaller than s->rem! */
+ //s->node.key = sw * s->next + s->rem - s->w;
+ //s->node.key = 65536 * s->next + s->rem - s->w;
+ //s->node.key = 256*s->next + (s->rem / 256);
+ //s->node.key = 256*s->next + ((s->rem - s->w) / 256);
+ s->node.key = 16*s->next + ((s->rem - s->w) / 4096);
+ eb32i_insert(&tree_0, &s->node);
+ s->tree = &tree_0;
+ }
+}
+
+/* prepares a server when extracting it from the init tree */
+static inline void get_srv_init(struct srv *s) {
+ s->next = s->rem = 0;
+}
+
+/* prepares a server when extracting it from the next tree */
+static inline void get_srv_next(struct srv *s) {
+ s->next += sw;
+}
+
+/* prepares a server when extracting it from the next tree */
+static inline void get_srv_down(struct srv *s) {
+ s->next = p;
+}
+
+/* prepares a server when extracting it from its tree */
+void get_srv(struct srv *s) {
+ if (s->tree == init_tree) {
+ get_srv_init(s);
+ }
+ else if (s->tree == next_tree) {
+ get_srv_next(s);
+ }
+ else if (s->tree == NULL) {
+ get_srv_down(s);
+ }
+}
+
+
+/* return next server from the current tree, or a server from the init tree
+ * if appropriate. If both trees are empty, return NULL.
+ */
+struct srv *get_next_server() {
+ struct eb32_node *node;
+ struct srv *s;
+
+ node = eb32_first(&tree_0);
+ s = eb32_entry(node, struct srv, node);
+
+ if (!node || s->next > p) {
+ /* either we have no server left, or we have a hole */
+ struct eb32_node *node2;
+ node2 = eb32_first(init_tree);
+ if (node2) {
+ node = node2;
+ s = eb32_entry(node, struct srv, node);
+ get_srv_init(s);
+ if (s->w == 0)
+ node = NULL;
+ }
+ }
+ if (node)
+ return s;
+ else
+ return NULL;
+}
+
+void update_position(struct srv *s) {
+ //if (s->tree == init_tree) {
+ if (!s->next) {
+ // first time ever for this server
+ s->last = p;
+ s->next = p + nsw / s->w;
+ s->rem += nsw % s->w;
+
+ if (s->rem >= s->w) {
+ s->rem -= s->w;
+ s->next++;
+ }
+ } else {
+ s->last = s->next; // or p ?
+ //s->next += sw / s->w;
+ //s->rem += sw % s->w;
+ s->next += nsw / s->w;
+ s->rem += nsw % s->w;
+
+ if (s->rem >= s->w) {
+ s->rem -= s->w;
+ s->next++;
+ }
+ }
+}
+
+
+/* switches trees init_tree and next_tree. init_tree should be empty when
+ * this happens, and next_tree filled with servers sorted by weights.
+ */
+void switch_trees() {
+ struct eb_root *swap;
+ swap = init_tree;
+ init_tree = next_tree;
+ next_tree = swap;
+ sw = nsw;
+ p = sw;
+}
+
+main(int argc, char **argv) {
+ int conns;
+ int i;
+
+ struct srv *s;
+
+ argc--; argv++;
+ nsrv = argc;
+
+ if (!nsrv)
+ exit(1);
+
+ srv = (struct srv *)calloc(nsrv, sizeof(struct srv));
+
+ sw = 0;
+ for (i = 0; i < nsrv; i++) {
+ s = &srv[i];
+ s->num = i;
+ s->w = atol(argv[i]);
+ sw += s->w;
+ }
+
+ nsw = sw;
+
+ init_tree = &tree_1;
+ next_tree = &tree_2;
+
+ /* and insert all the servers in the PREV tree */
+ /* note that it is required to insert them according to
+ * the reverse order of their weights.
+ */
+ printf("---------------:");
+ for (i = 0; i < nsrv; i++) {
+ s = &srv[i];
+ queue_by_weight_0(init_tree, s);
+ printf("%2d", s->w);
+ }
+ printf("\n");
+
+ p = sw; // time base of current tree
+ conns = 0;
+ while (1) {
+ struct eb32_node *node;
+
+ printf("%08d|%06d: ", conns, p);
+
+ /* if we have en empty tree, let's first try to collect weights
+ * which might have changed.
+ */
+ if (!sw) {
+ if (nsw) {
+ sw = nsw;
+ p = sw;
+ /* do not switch trees, otherwise new servers (from init)
+ * would end up in next.
+ */
+ //switch_trees();
+ //printf("bla\n");
+ }
+ else
+ goto next_iteration;
+ }
+
+ s = get_next_server();
+ if (!s) {
+ printf("----------- switch (empty) -- sw=%d -> %d ---------\n", sw, nsw);
+ switch_trees();
+ s = get_next_server();
+ printf("%08d|%06d: ", conns, p);
+
+ if (!s)
+ goto next_iteration;
+ }
+ else if (s->next >= 2*sw) {
+ printf("ARGGGGG! s[%d].next=%d, max=%d\n", s->num, s->next, 2*sw-1);
+ }
+
+ /* now we have THE server we want to put at this position */
+ for (i = 0; i < s->num; i++) {
+ if (srv[i].w > 0)
+ printf(". ");
+ else
+ printf("_ ");
+ }
+ printf("# ");
+ for (i = s->num + 1; i < nsrv; i++) {
+ if (srv[i].w > 0)
+ printf(". ");
+ else
+ printf("_ ");
+ }
+ printf(" : ");
+
+ printf("s=%02d v=%04d w=%03d n=%03d r=%03d ",
+ s->num, s->node.key, s->w, s->next, s->rem);
+
+ update_position(s);
+ printf(" | next=%03d, rem=%03d ", s->next, s->rem);
+
+ if (s->next >= sw * 2) {
+ dequeue_srv(s);
+ //queue_by_weight(next_tree, s);
+ put_srv(s);
+ printf(" => next (w=%d, n=%d) ", s->w, s->next);
+ }
+ else {
+ printf(" => curr ");
+
+ //s->node.key = s->next;
+ /* we want to ensure that in case of conflicts, servers with
+ * the highest weights will get served first. Also, we still
+ * have the remainder to see where the entry expected to be
+ * inserted.
+ */
+ //s->node.key = 256 * s->next + 255 - s->w;
+ //s->node.key = sw * s->next + sw / s->w;
+ //s->node.key = sw * s->next + s->rem; /// seems best (check with filltab15) !
+
+ //s->node.key = (2 * sw * s->next) + s->rem + sw / s->w;
+
+ /* FIXME: must be optimized */
+ dequeue_srv(s);
+ put_srv(s);
+ //eb32i_insert(&tree_0, &s->node);
+ //s->tree = &tree_0;
+ }
+
+ next_iteration:
+ p++;
+ conns++;
+ if (/*conns == 30*/ /**/random()%1000 == 0/**/) {
+ int w = /*20*//**/random()%10000/**/;
+ int num = /*1*//**/random()%nsrv/**/;
+ struct srv *s = &srv[num];
+
+ nsw = nsw - s->w + w;
+ //sw=nsw;
+
+ if (s->tree == init_tree) {
+ printf(" -- chgwght1(%d): %d->%d, n=%d --", s->num, s->w, w, s->next);
+ printf("(init)");
+ s->w = w;
+ dequeue_srv(s);
+ queue_by_weight_0(s->tree, s);
+ }
+ else if (s->tree == NULL) {
+ printf(" -- chgwght2(%d): %d->%d, n=%d --", s->num, s->w, w, s->next);
+ printf("(down)");
+ s->w = w;
+ dequeue_srv(s);
+ //queue_by_weight_0(init_tree, s);
+ get_srv(s);
+ s->next = p + (nsw + sw - p) / s->w;
+ put_srv(s);
+ }
+ else {
+ int oldnext;
+
+ /* the server is either active or in the next queue */
+ get_srv(s);
+ printf(" -- chgwght3(%d): %d->%d, n=%d, sw=%d, nsw=%d --", s->num, s->w, w, s->next, sw, nsw);
+
+ oldnext = s->next;
+ s->w = w;
+
+ /* we must measure how far we are from the end of the current window
+ * and try to fit their as many entries as should theorically be.
+ */
+
+ //s->w = s->w * (2*sw - p) / sw;
+ if (s->w > 0) {
+ int step = (nsw /*+ sw - p*/) / s->w;
+ s->next = s->last + step;
+ s->rem = 0;
+ if (s->next > oldnext) {
+ s->next = oldnext;
+ printf(" aaaaaaa ");
+ }
+
+ if (s->next < p + 2) {
+ s->next = p + step;
+ printf(" bbbbbb ");
+ }
+ } else {
+ printf(" push -- ");
+ /* push it into the next tree */
+ s->w = 0;
+ s->next = p + sw;
+ }
+
+
+ dequeue_srv(s);
+ printf(" n=%d", s->next);
+ put_srv(s);
+ }
+ }
+
+ printf("\n");
+
+ if (0 && conns % 50000 == 0) {
+ printf("-------- %-5d : changing all weights ----\n", conns);
+
+ for (i = 0; i < nsrv; i++) {
+ int w = i + 1;
+ s = &srv[i];
+ nsw = nsw - s->w + w;
+ s->w = w;
+ dequeue_srv(s);
+ queue_by_weight_0(next_tree, s); // or init_tree ?
+ }
+ }
+
+ }
+}
+
projects / thirdparty / haproxy.git / commitdiff
