Maintenance: Upgrade MEM_DREAD_CTRL memory pool

 ... to a MEMPROXY class pool.

Replacing memory allocate and destruct with C++ new/delete
and in-class initialization.

src/fs_io.cc

@@ -364,7 +364,7 @@ diskHandleRead(int fd, void *data)
      */
 
     if (fd < 0) {
-        memFree(ctrl_dat, MEM_DREAD_CTRL);
+        delete ctrl_dat;
         return;
     }
 
@@ -414,7 +414,7 @@ diskHandleRead(int fd, void *data)
 
     cbdataReferenceDone(ctrl_dat->client_data);
 
-    memFree(ctrl_dat, MEM_DREAD_CTRL);
+    delete ctrl_dat;
 }
 
 /* start read operation */
@@ -424,14 +424,12 @@ diskHandleRead(int fd, void *data)
 void
 file_read(int fd, char *buf, int req_len, off_t offset, DRCB * handler, void *client_data)
 {
-    dread_ctrl *ctrl_dat;
     assert(fd >= 0);
-    ctrl_dat = (dread_ctrl *)memAllocate(MEM_DREAD_CTRL);
+    auto *ctrl_dat = new dread_ctrl;
     ctrl_dat->fd = fd;
     ctrl_dat->offset = offset;
     ctrl_dat->req_len = req_len;
     ctrl_dat->buf = buf;
-    ctrl_dat->end_of_file = 0;
     ctrl_dat->handler = handler;
     ctrl_dat->client_data = cbdataReference(client_data);
     diskHandleRead(fd, ctrl_dat);

src/fs_io.h

@@ -17,17 +17,18 @@
 
 class MemBuf;
 
-// POD
 class dread_ctrl
 {
+    MEMPROXY_CLASS(dread_ctrl);
+
 public:
-    int fd;
-    off_t offset;
-    int req_len;
-    char *buf;
-    int end_of_file;
-    DRCB *handler;
-    void *client_data;
+    int fd = -1;
+    off_t offset = 0;
+    int req_len = 0;
+    char *buf = nullptr;
+    int end_of_file = 0;
+    DRCB *handler = {};
+    void *client_data = {};
 };
 
 class dwrite_q

src/mem/forward.h

@@ -51,7 +51,6 @@ typedef enum {
     MEM_16K_BUF,
     MEM_32K_BUF,
     MEM_64K_BUF,
-    MEM_DREAD_CTRL,
     MEM_MD5_DIGEST,
     MEM_MAX
 } mem_type;

src/mem/old_api.cc

@@ -308,7 +308,6 @@ Mem::Init(void)
     memDataInit(MEM_32K_BUF, "32K Buffer", 32768, 10, false);
     memDataInit(MEM_64K_BUF, "64K Buffer", 65536, 10, false);
     // TODO: Carefully stop zeroing these objects memory and drop the doZero parameter
-    memDataInit(MEM_DREAD_CTRL, "dread_ctrl", sizeof(dread_ctrl), 0, true);
     memDataInit(MEM_MD5_DIGEST, "MD5 digest", SQUID_MD5_DIGEST_LENGTH, 0, true);
     GetPool(MEM_MD5_DIGEST)->setChunkSize(512 * 1024);