Add shared memory hit counter example to redbean

test/tool/net/mapshared_test.lua

@@ -29,7 +29,7 @@ assert(mem:read() == 'hello')
 mem:write('hi')
 assert(mem:read() == 'hi')
 assert(mem:read(0, 5) == 'hi\0lo')
-mem:write('H', 0, 1)
+mem:write(0, 'H', 1)
 assert(mem:read(0, 5) == 'Hi\0lo')
 assert(mem:read(1, 1) == 'i')
 

third_party/lua/lunix.c

@@ -2696,19 +2696,29 @@ static int LuaUnixMemoryRead(lua_State *L) {
   return 1;
 }
 
-// unix.Memory:write(data:str[, offset:int[, bytes:int]])
+// unix.Memory:write([offset:int,] data:str[, bytes:int])
 static int LuaUnixMemoryWrite(lua_State *L) {
+  int b;
   const char *s;
   size_t i, n, j;
   struct Memory *m;
   m = luaL_checkudata(L, 1, "unix.Memory");
-  s = luaL_checklstring(L, 2, &n);
-  i = luaL_optinteger(L, 3, 0);
+  if (!lua_isnumber(L, 2)) {
+    // unix.Memory:write(data:str[, bytes:int])
+    i = 0;
+    s = luaL_checklstring(L, 2, &n);
+    b = 3;
+  } else {
+    // unix.Memory:write(offset:int, data:str[, bytes:int])
+    i = luaL_checkinteger(L, 2);
+    s = luaL_checklstring(L, 3, &n);
+    b = 4;
+  }
   if (i > m->size) {
     luaL_error(L, "out of range");
     unreachable;
   }
-  if (lua_isnoneornil(L, 4)) {
+  if (lua_isnoneornil(L, b)) {
     // unix.Memory:write(data:str[, offset:int])
     // writes binary data, plus a nul terminator
     if (i < n < m->size) {
@@ -2723,9 +2733,9 @@ static int LuaUnixMemoryWrite(lua_State *L) {
   } else {
     // unix.Memory:write(data:str, offset:int, bytes:int])
     // writes binary data without including nul-terminator
-    j = luaL_checkinteger(L, 4);
+    j = luaL_checkinteger(L, b);
     if (j > n) {
-      luaL_argerror(L, 4, "bytes is more than what's in data");
+      luaL_argerror(L, b, "bytes is more than what's in data");
       unreachable;
     }
     n = j;

tool/net/demo/.init.lua

@@ -20,35 +20,73 @@ db:exec[[
   INSERT INTO test (content) VALUES ('Hello Sqlite3');
 ]]
 
+-- shared memory hit counter
+SHM_LOCK = 0  -- index zero (first eight bytes) will hold mutex
+SHM_JSON = 8  -- store json payload starting at the index eight
+shm = unix.mapshared(65520)
+function Lock()
+    local ok, old = shm:cmpxchg(SHM_LOCK, 0, 1)
+    if not ok then
+        if old == 1 then
+            old = shm:xchg(SHM_LOCK, 2)
+        end
+        while old > 0 do
+            shm:wait(SHM_LOCK, 2)
+            old = shm:xchg(SHM_LOCK, 2)
+        end
+    end
+end
+function Unlock()
+    old = shm:fetch_add(SHM_LOCK, -1)
+    if old == 2 then
+        shm:store(SHM_LOCK, 0)
+        shm:wake(SHM_LOCK, 1)
+    end
+end
+
 function OnServerListen(fd, ip, port)
-   unix.setsockopt(fd, unix.SOL_TCP, unix.TCP_SAVE_SYN, true)
-   return false
+    unix.setsockopt(fd, unix.SOL_TCP, unix.TCP_SAVE_SYN, true)
+    return false
 end
 
 function OnClientConnection(ip, port, serverip, serverport)
-   syn, synerr = unix.getsockopt(GetClientFd(), unix.SOL_TCP, unix.TCP_SAVED_SYN)
+    syn, synerr = unix.getsockopt(GetClientFd(), unix.SOL_TCP, unix.TCP_SAVED_SYN)
+end
+
+function UpdateHitCounter()
+    local s, t, k
+    Lock()
+    s = shm:read(SHM_JSON)
+    if s == '' then s = '{}' end
+    t = DecodeJson(s)
+    k = GetPath()
+    if not t[k] then t[k] = 0 end
+    t[k] = t[k] + 1
+    shm:write(SHM_JSON, EncodeJson(t))
+    Unlock()
 end
 
 -- this intercepts all requests if it's defined
 function OnHttpRequest()
-   if GetHeader('User-Agent') then
-      Log(kLogInfo, "client is running %s and reports %s" % {
-             finger.GetSynFingerOs(finger.FingerSyn(syn)),
-             VisualizeControlCodes(GetHeader('User-Agent'))})
-   end
-   if HasParam('magic') then
-      Write('<p>\r\n')
-      Write('OnHttpRequest() has intercepted your request<br>\r\n')
-      Write('because you specified the magic parameter\r\n')
-      Write('<pre>\r\n')
-      Write(EscapeHtml(LoadAsset('/.init.lua')))
-      Write('</pre>\r\n')
-   else
-      Route() -- this asks redbean to do the default thing
-   end
-   SetHeader('Server', 'redbean!')
+    UpdateHitCounter()
+    if GetHeader('User-Agent') then
+        Log(kLogInfo, "client is running %s and reports %s" % {
+                finger.GetSynFingerOs(finger.FingerSyn(syn)),
+                VisualizeControlCodes(GetHeader('User-Agent'))})
+    end
+    if HasParam('magic') then
+        Write('<p>\r\n')
+        Write('OnHttpRequest() has intercepted your request<br>\r\n')
+        Write('because you specified the magic parameter\r\n')
+        Write('<pre>\r\n')
+        Write(EscapeHtml(LoadAsset('/.init.lua')))
+        Write('</pre>\r\n')
+    else
+        Route() -- this asks redbean to do the default thing
+    end
+    SetHeader('Server', 'redbean!')
 end
 
 function Adder(x, y)
-   return x + y
+    return x + y
 end

tool/net/demo/hitcounter.lua

@@ -0,0 +1,35 @@
+Write([[<!doctype html>
+<title>redbean mapshared demo</title>
+<style>
+  body { padding: 1em; }
+  h1 a { color: inherit; text-decoration: none; }
+  h1 img { border: none; vertical-align: middle; }
+  input { margin: 1em; padding: .5em; }
+  pre { margin-left: 2em; }
+  p { word-break: break-word; max-width: 650px; }
+  dt { font-weight: bold; }
+  dd { margin-top: 1em; margin-bottom: 1em; }
+  .hdr { text-indent: -1em; padding-left: 1em; }
+</style>
+<h1>
+  <a href="/"><img src="/redbean.png"></a>
+  <a href="fetch.lua">redbean mapshared demo</a>
+</h1>
+<p>
+  This page displays a <code>unix.mapshared()</code> hit counter of
+  the <code>GetPath()</code>.
+</p>
+<dl>
+]])
+
+Lock()
+s = shm:read(SHM_JSON)
+if s == '' then s = '{}' end
+t = DecodeJson(s)
+Unlock()
+
+for k,v in pairs(t) do
+    Write('<dt>%s<dd>%d\n' % {EscapeHtml(k), v})
+end
+
+Write('</dl>')

tool/net/help.txt

@@ -4509,7 +4509,7 @@ UNIX MODULE
             end
         end
         function Unlock()
-            old = mem:add(LOCK, -1)
+            old = mem:fetch_add(LOCK, -1)
             if old == 2 then
                 mem:store(LOCK, 0)
                 mem:wake(LOCK, 1)
@@ -4568,7 +4568,7 @@ UNIX MODULE
     single lock which is used to synchronize reads and writes to
     that specific map. To make it scale, create additional maps.
 
-  unix.Memory:write(data:str[, offset:int[, bytes:int]])
+  unix.Memory:write([offset:int,] data:str[, bytes:int]])
 
     Writes bytes to memory region.
 

tool/net/net.mk

@@ -154,6 +154,7 @@ o/$(MODE)/tool/net/demo/store-asset.lua.zip.o					\
 o/$(MODE)/tool/net/demo/maxmind.lua.zip.o					\
 o/$(MODE)/tool/net/demo/redbean.lua.zip.o					\
 o/$(MODE)/tool/net/demo/opensource.lua.zip.o					\
+o/$(MODE)/tool/net/demo/hitcounter.lua.zip.o					\
 o/$(MODE)/tool/net/demo/binarytrees.lua.zip.o					\
 o/$(MODE)/tool/net/demo/crashreport.lua.zip.o					\
 o/$(MODE)/tool/net/demo/closedsource.lua.zip.o					\
@@ -205,6 +206,7 @@ o/$(MODE)/tool/net/redbean-demo.com.dbg:					\
 		o/$(MODE)/tool/net/demo/redbean.lua.zip.o			\
 		o/$(MODE)/tool/net/demo/maxmind.lua.zip.o			\
 		o/$(MODE)/tool/net/demo/opensource.lua.zip.o			\
+		o/$(MODE)/tool/net/demo/hitcounter.lua.zip.o			\
 		o/$(MODE)/tool/net/demo/binarytrees.lua.zip.o			\
 		o/$(MODE)/tool/net/demo/crashreport.lua.zip.o			\
 		o/$(MODE)/tool/net/demo/closedsource.lua.zip.o			\