VSI_CACHE_SIZE: Use CPLParseMemorySize

Author: dbaston

autotest/gcore/vsifile.py

@@ -237,16 +237,16 @@ def test_vsifile_4():
 # Test vsicache
 
 
-@pytest.mark.parametrize("cache_size", ("0", "65536", None))
-def test_vsifile_5(cache_size):
+@pytest.mark.parametrize("cache_size", ("0", "64kb", None))
+def test_vsifile_5(tmp_path, cache_size):
 
-    fp = gdal.VSIFOpenL("tmp/vsifile_5.bin", "wb")
+    fp = gdal.VSIFOpenL(tmp_path / "vsifile_5.bin", "wb")
     ref_data = "".join(["%08X" % i for i in range(5 * 32768)])
     gdal.VSIFWriteL(ref_data, 1, len(ref_data), fp)
     gdal.VSIFCloseL(fp)
 
     with gdal.config_options({"VSI_CACHE": "YES", "VSI_CACHE_SIZE": cache_size}):
-        fp = gdal.VSIFOpenL("tmp/vsifile_5.bin", "rb")
+        fp = gdal.VSIFOpenL(tmp_path / "vsifile_5.bin", "rb")
 
         gdal.VSIFSeekL(fp, 50000, 0)
         if gdal.VSIFTellL(fp) != 50000:
@@ -277,8 +277,6 @@ def test_vsifile_5(cache_size):
 
         gdal.VSIFCloseL(fp)
 
-    gdal.Unlink("tmp/vsifile_5.bin")
-
 
 ###############################################################################
 # Test vsicache an read errors (https://github.com/qgis/QGIS/issues/45293)

doc/source/user/configoptions.rst

@@ -321,6 +321,9 @@ Performance and caching
       Set the size of the VSI cache. Be wary of large values for
       ``VSI_CACHE_SIZE`` when opening VRT datasources containing many source
       rasters, as this is a per-file cache.
+      Since GDAL 3.11, the value of ``VSI_CACHE_SIZE`` may be specified using
+      memory units (e.g., "25 MB").
+
 
 Driver management
 ^^^^^^^^^^^^^^^^^

port/cpl_vsil_cache.cpp

@@ -112,13 +112,30 @@ class VSICachedFile final : public VSIVirtualHandle
 
 static size_t GetCacheMax(size_t nCacheSize)
 {
-    return nCacheSize ? nCacheSize
-                      : static_cast<size_t>(std::min(
-                            static_cast<GUIntBig>(
-                                std::numeric_limits<size_t>::max() / 2),
-                            CPLScanUIntBig(CPLGetConfigOption("VSI_CACHE_SIZE",
-                                                              "25000000"),
-                                           40)));
+    if (nCacheSize)
+    {
+        return nCacheSize;
+    }
+
+    const char *pszCacheSize = CPLGetConfigOption("VSI_CACHE_SIZE", "25000000");
+    GIntBig nMemorySize;
+    bool bUnitSpecified;
+    if (CPLParseMemorySize(pszCacheSize, &nMemorySize, &bUnitSpecified) !=
+        CE_None)
+    {
+        CPLError(
+            CE_Failure, CPLE_IllegalArg,
+            "Failed to parse value of VSI_CACHE_SIZE. Using default of 25MB");
+        nMemorySize = 25000000;
+    }
+    else if (static_cast<size_t>(nMemorySize) >
+             std::numeric_limits<size_t>::max() / 2)
+    {
+        nMemorySize =
+            static_cast<GIntBig>(std::numeric_limits<size_t>::max() / 2);
+    }
+
+    return static_cast<size_t>(nMemorySize);
 }
 
 /************************************************************************/