Lend a text state's stored extents for its view (079)

A view that shows a text state as it is (pure_module_text_state) now goes
out as the state's stored extents, as a document read does: the answer
holds the store mapping, charged to the budget, until it is sent and its
ticket released; a state with edits not yet stored is copied as before.
Documents and views share one loan path, and the extent array grows as
needed. A 1 MiB note read by 8 connections: 776-817 answers a second
copied, 1,875-1,901 lent, p50 9.2 to 3.5 ms, peak RSS 10.3 to 5.7 MiB.
The load generator learns GET /views/page.

1 files changed, 9 insertions, 8 deletions

diff --git a/benchmarks/http/load.c b/benchmarks/http/load.c
index fd074e8..fe50deb 100644
--- a/benchmarks/http/load.c
+++ b/benchmarks/http/load.c
@@ -2,14 +2,15 @@
 /* HTTP/1.1 load for Pure's benchmarks: N connections on one epoll thread,
  * each sending one request at a time and measuring its latency.
  *
- * load PORT CONNECTIONS SECONDS get|put|score|total|page KEYS [keep-alive|close] [BODY]
+ * load PORT CONNECTIONS SECONDS get|put|score|total|page|note KEYS [keep-alive|close] [BODY]
  * get: GET /objects/kI for I in [0, KEYS).
  * put: connection C edits its own key kC (C mod KEYS), inserting BODY bytes
  *      at 0 with If-Match on the revision it last saw (If-None-Match: * at
  *      first); a 412 takes the revision from the ETag and tries again.
  * The scoreboard app: score posts a point for kC (POST /inputs/score?points=1,
  * the name as the body), total reads GET /views/total and page GET
- * /views/leaders?from=0&count=20.
+ * /views/leaders?from=0&count=20. note reads GET /views/page (a text state
+ * shown as it is, as in a notes app).
  * Prints one JSON line: requests/s, statuses, latency percentiles (µs). */
 #include <arpa/inet.h>
 #include <errno.h>
@@ -67,7 +68,7 @@ static uint64_t percentile(uint64_t total, double p) {
 }
 
 static int port, connections_count, keys;
-static enum { GET, PUT, SCORE, TOTAL, PAGE } method;
+static enum { GET, PUT, SCORE, TOTAL, PAGE, NOTE } method;
 static bool put, keep_alive;
 static char *body;
 static size_t body_bytes;
@@ -82,7 +83,7 @@ static void prepare(Connection *c) {
             snprintf(c->request, sizeof(c->request), "POST /inputs/score?points=1 HTTP/1.1\r\nHost: localhost\r\n"
                      "Content-Length: %d\r\n%s\r\n%s", length, closing, name) :
             snprintf(c->request, sizeof(c->request), "GET /views/%s HTTP/1.1\r\nHost: localhost\r\n%s\r\n",
-                     method == TOTAL ? "total" : "leaders?from=0&count=20", closing));
+                     method == TOTAL ? "total" : method == NOTE ? "page" : "leaders?from=0&count=20", closing));
         c->sent = c->received = c->body_sent = c->body_size = 0;
         c->started = now_us();
         return;
@@ -140,15 +141,15 @@ static bool complete(Connection *c, int *status, bool *closing, size_t *length)
 
 int main(int argc, char **argv) {
     if (argc < 6) {
-        fputs("load PORT CONNECTIONS SECONDS get|put|score|total|page KEYS [keep-alive|close] [BODY]\n", stderr);
+        fputs("load PORT CONNECTIONS SECONDS get|put|score|total|page|note KEYS [keep-alive|close] [BODY]\n", stderr);
         return 2;
     }
     port = atoi(argv[1]);
     connections_count = atoi(argv[2]);
     double seconds = atof(argv[3]);
-    static const char *const methods[] = {"get", "put", "score", "total", "page"};
-    for (method = GET; method <= PAGE && strcmp(argv[4], methods[method]); ++method) {}
-    if (method > PAGE) { fprintf(stderr, "load: unknown method %s\n", argv[4]); return 2; }
+    static const char *const methods[] = {"get", "put", "score", "total", "page", "note"};
+    for (method = GET; method <= NOTE && strcmp(argv[4], methods[method]); ++method) {}
+    if (method > NOTE) { fprintf(stderr, "load: unknown method %s\n", argv[4]); return 2; }
     put = method == PUT;
     keys = atoi(argv[5]);
     keep_alive = argc > 6 && !strcmp(argv[6], "keep-alive");