[Request] [++ ] D8644: util: provide a helper function to estimate RAM size

[joerg.sonnenberger (Joerg Sonnenberger)]

joerg.sonnenberger created this revision.
Herald added a reviewer: hg-reviewers.
Herald added a subscriber: mercurial-patches.

REVISION SUMMARY
  For POSIX systems, it uses sysconf. For Windows, it uses the win32 API
  directly.

REPOSITORY
  rHG Mercurial

BRANCH
  stable

REVISION DETAIL
  https://phab.mercurial-scm.org/D8644

AFFECTED FILES
  mercurial/configitems.py
  mercurial/util.py

CHANGE DETAILS

diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -3626,3 +3626,47 @@
         if not (byte & 0x80):
             return result
         shift += 7
+
+
+def estimatememory(ui):
+    """Provide an estimate for the available system memory in Bytes.
+
+    If no estimate can be provided on the platform, returns None.
+    """
+    value = ui.config(b'ui', b'available-memory')
+    if value is not None:
+        try:
+            return sizetoint(value)
+        except error.ParseError:
+            raise error.ConfigError(
+                _(b"ui.available-memory value is invalid ('%s')") % value
+            )
+    try:
+        pagesize = os.sysconf(os.sysconf_names['SC_PAGE_SIZE'])
+        pages = os.sysconf(os.sysconf_names['SC_PHYS_PAGES'])
+        return pagesize * pages
+    except OSError:
+        pass
+    except KeyError:
+        pass
+    if pycompat.sysplatform.startswith(b'win'):
+        from ctypes import c_long as DWORD, c_ulonglong as DWORDLONG
+        from ctypes.wintypes import Structure, byref, sizeof, windll
+
+        class MEMORYSTATUSEX(Structure):
+            _fields_ = [
+                ('dwLength', DWORD),
+                ('dwMemoryLoad', DWORD),
+                ('ullTotalPhys', DWORDLONG),
+                ('ullAvailPhys', DWORDLONG),
+                ('ullTotalPageFile', DWORDLONG),
+                ('ullAvailPageFile', DWORDLONG),
+                ('ullTotalVirtual', DWORDLONG),
+                ('ullAvailVirtual', DWORDLONG),
+                ('ullExtendedVirtual', DWORDLONG),
+            ]
+
+        x = MEMORYSTATUSEX()
+        x.dwLength = sizeof(x)
+        windll.kernel32.GlobalMemoryStatusEx(byref(x))
+        return x.ullAvailPhys
diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -1231,6 +1231,10 @@
     b'ui', b'askusername', default=False,
 )
 coreconfigitem(
+    b'ui', b'available-memory', default=None,
+)
+
+coreconfigitem(
     b'ui', b'clonebundlefallback', default=False,
 )
 coreconfigitem(



To: joerg.sonnenberger, #hg-reviewers
Cc: mercurial-patches, mercurial-devel
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