From f00cf43d14c9a4bc75ed4d506ca182b30bf023c9 Mon Sep 17 00:00:00 2001
From: Craig Warren <craig_warren@me.com>
Date: Thu, 4 Aug 2016 15:59:34 +0100
Subject: [PATCH] Added error check for when model could use more RAM than
 available.

---
 gprMax/input_cmds_singleuse.py | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/gprMax/input_cmds_singleuse.py b/gprMax/input_cmds_singleuse.py
index 100dec48..f41a59c5 100644
--- a/gprMax/input_cmds_singleuse.py
+++ b/gprMax/input_cmds_singleuse.py
@@ -19,11 +19,12 @@
 import os
 import psutil
 import decimal as d
+import sys
 
 import numpy as np
 
 from gprMax.constants import c, floattype
-from gprMax.exceptions import CmdInputError
+from gprMax.exceptions import CmdInputError, GeneralError
 from gprMax.utilities import round_value, human_size
 from gprMax.waveforms import Waveform
 
@@ -112,33 +113,38 @@ def process_singlecmds(singlecmds, G):
         raise CmdInputError(cmd + ' requires at least one cell in every dimension')
     if G.messages:
         print('Domain size: {:g} x {:g} x {:g}m ({:d} x {:d} x {:d} = {:g} cells)'.format(tmp[0], tmp[1], tmp[2], G.nx, G.ny, G.nz, (G.nx * G.ny * G.nz)))
-        # Guesstimate at memory usage
-        mem = (((G.nx + 1) * (G.ny + 1) * (G.nz + 1) * 13 * np.dtype(floattype).itemsize + (G.nx + 1) * (G.ny + 1) * (G.nz + 1) * 18) * 1.1) + 30e6
-        print('Memory (RAM) usage: ~{} required, {} available'.format(human_size(mem), human_size(psutil.virtual_memory().total)))
+    
+    # Estimate memory (RAM) usage
+    if G.messages:
+        # Currently this is a pretty loose estimate but seems to match reasonably with memory usage reported when model completes.
+        memestimate = (((G.nx + 1) * (G.ny + 1) * (G.nz + 1) * 13 * np.dtype(floattype).itemsize + (G.nx + 1) * (G.ny + 1) * (G.nz + 1) * 18) * 1.1) + 30e6
+        print('Memory (RAM) usage: ~{} required, {} available'.format(human_size(memestimate), human_size(psutil.virtual_memory().total)))
+    if memestimate > psutil.virtual_memory().total:
+        raise GeneralError('Estimated memory (RAM) required ~{} exceeds {} available!\n'.format(human_size(memestimate), human_size(psutil.virtual_memory().total)))
 
     # Time step CFL limit (use either 2D or 3D) and default PML thickness
     if G.nx == 1:
         G.dt = 1 / (c * np.sqrt((1 / G.dy) * (1 / G.dy) + (1 / G.dz) * (1 / G.dz)))
-        G.dtlimit = '2D'
+        gridtype = '2D'
         G.pmlthickness = (0, G.pmlthickness, G.pmlthickness, 0, G.pmlthickness, G.pmlthickness)
     elif G.ny == 1:
         G.dt = 1 / (c * np.sqrt((1 / G.dx) * (1 / G.dx) + (1 / G.dz) * (1 / G.dz)))
-        G.dtlimit = '2D'
+        gridtype = '2D'
         G.pmlthickness = (G.pmlthickness, 0, G.pmlthickness, G.pmlthickness, 0, G.pmlthickness)
     elif G.nz == 1:
         G.dt = 1 / (c * np.sqrt((1 / G.dx) * (1 / G.dx) + (1 / G.dy) * (1 / G.dy)))
-        G.dtlimit = '2D'
+        gridtype = '2D'
         G.pmlthickness = (G.pmlthickness, G.pmlthickness, 0, G.pmlthickness, G.pmlthickness, 0)
     else:
         G.dt = 1 / (c * np.sqrt((1 / G.dx) * (1 / G.dx) + (1 / G.dy) * (1 / G.dy) + (1 / G.dz) * (1 / G.dz)))
-        G.dtlimit = '3D'
+        gridtype = '3D'
         G.pmlthickness = (G.pmlthickness, G.pmlthickness, G.pmlthickness, G.pmlthickness, G.pmlthickness, G.pmlthickness)
 
     # Round down time step to nearest float with precision one less than hardware maximum. Avoids inadvertently exceeding the CFL due to binary representation of floating point number.
     G.dt = round_value(G.dt, decimalplaces=d.getcontext().prec - 1)
 
     if G.messages:
-        print('Time step (at {} CFL limit): {:g} secs'.format(G.dtlimit, G.dt))
+        print('Time step (at {} CFL limit): {:g} secs'.format(gridtype, G.dt))
 
     # Time step stability factor
     cmd = '#time_step_stability_factor'