support determine available memory for FreeBSD

base/base/CMakeLists.txt

@@ -2,6 +2,7 @@ set (SRCS
     argsToConfig.cpp
     coverage.cpp
     demangle.cpp
+    getAvailableMemoryAmount.cpp
     getFQDNOrHostName.cpp
     getMemoryAmount.cpp
     getPageSize.cpp

base/base/getAvailableMemoryAmount.cpp

@@ -0,0 +1,41 @@
+#include <stdexcept>
+#include <fstream>
+#include <base/getAvailableMemoryAmount.h>
+#include <base/getPageSize.h>
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/param.h>
+#if defined(BSD)
+#include <sys/sysctl.h>
+#include <sys/vmmeter.h>
+#endif
+
+
+uint64_t getAvailableMemoryAmountOrZero()
+{
+    int64_t page_size = getPageSize();
+    if (page_size <= 0)
+        return 0;
+
+#if defined(__FreeBSD__)
+    struct vmtotal vmt;
+    size_t vmt_size = sizeof(vmt);
+    if (sysctlbyname("vm.vmtotal", &vmt, &vmt_size, NULL, 0) < 0)
+       return 0;
+    uint64_t available_pages = vmt.t_avm;
+#else
+    uint64_t available_pages = sysconf(_SC_AVPHYS_PAGES);
+#endif
+
+    return page_size * available_pages;
+}
+
+
+uint64_t getAvailableMemoryAmount()
+{
+    auto res = getAvailableMemoryAmountOrZero();
+    if (!res)
+        throw std::runtime_error("Cannot determine available memory amount");
+    return res;
+}

base/base/getAvailableMemoryAmount.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include <cstdint>
+
+/** Returns the size of currently available physical memory (RAM) in bytes.
+  * Returns 0 on unsupported platform or if it cannot determine the size of physical memory.
+  */
+uint64_t getAvailableMemoryAmountOrZero();
+
+/** Throws exception if it cannot determine the size of physical memory.
+  */
+uint64_t getAvailableMemoryAmount();

programs/server/Server.cpp

@@ -20,6 +20,7 @@
 #include <base/phdr_cache.h>
 #include <base/ErrorHandlers.h>
 #include <base/getMemoryAmount.h>
+#include <base/getAvailableMemoryAmount.h>
 #include <base/errnoToString.h>
 #include <base/coverage.h>
 #include <Common/ClickHouseRevision.h>
@@ -588,8 +589,14 @@ static void sanityChecks(Server* server)
     if (getBlockDeviceType(dev_id) == BlockDeviceType::ROT && getBlockDeviceReadAheadBytes(dev_id) == 0)
         server->context()->addWarningMessage("Rotational disk with disabled readahead is in use. Performance can be degraded.");
 #endif
-    if (sysconf(_SC_AVPHYS_PAGES) * sysconf(_SC_PAGE_SIZE) < (2l << 30))
-        server->context()->addWarningMessage("Available memory at server startup is too low (2GiB).");
+    try
+    {
+        if (getAvailableMemoryAmount() < (2l << 30))
+            server->context()->addWarningMessage("Available memory at server startup is too low (2GiB).");
+    }
+    catch (...)
+    {
+    }
 
     if (!enoughSpaceInDirectory(data_path, 1ull << 30))
         server->context()->addWarningMessage("Available disk space at server startup is too low (1GiB).");