VRTSourcedRasterBand::GetMinimum/GetMaximum(): limit to 1 second max …

…when iterating over sources
OSGeo · Oct 26, 2023 · 2ba9ef9 · 2ba9ef9
1 parent 5d3638a
commit 2ba9ef9
Showing 1 changed file with 83 additions and 1 deletion.
diff --git a/frmts/vrt/vrtsourcedrasterband.cpp b/frmts/vrt/vrtsourcedrasterband.cpp
@@ -535,6 +535,37 @@ CPLErr VRTSourcedRasterBand::IReadBlock(int nBlockXOff, int nBlockYOff,
                      nPixelSize * nBlockXSize, &sExtraArg);
 }
 
+/************************************************************************/
+/*                        CPLGettimeofday()                             */
+/************************************************************************/
+
+#if defined(_WIN32) && !defined(__CYGWIN__)
+#include <sys/timeb.h>
+
+namespace
+{
+struct CPLTimeVal
+{
+    time_t tv_sec; /* seconds */
+    long tv_usec;  /* and microseconds */
+};
+}  // namespace
+
+static int CPLGettimeofday(struct CPLTimeVal *tp, void * /* timezonep*/)
+{
+    struct _timeb theTime;
+
+    _ftime(&theTime);
+    tp->tv_sec = static_cast<time_t>(theTime.time);
+    tp->tv_usec = theTime.millitm * 1000;
+    return 0;
+}
+#else
+#include <sys/time.h> /* for gettimeofday() */
+#define CPLTimeVal timeval
+#define CPLGettimeofday(t, u) gettimeofday(t, u)
+#endif
+
 /************************************************************************/
 /*                    CanUseSourcesMinMaxImplementations()              */
 /************************************************************************/
@@ -552,6 +583,10 @@ bool VRTSourcedRasterBand::CanUseSourcesMinMaxImplementations()
     // on the filesystem, whose open time and GetMinimum()/GetMaximum()
     // implementations we hope to be fast enough.
     // In case of doubt return FALSE.
+    struct CPLTimeVal tvStart;
+    memset(&tvStart, 0, sizeof(CPLTimeVal));
+    if (nSources > 1)
+        CPLGettimeofday(&tvStart, nullptr);
     for (int iSource = 0; iSource < nSources; iSource++)
     {
         if (!(papoSources[iSource]->IsSimpleSource()))
@@ -572,7 +607,7 @@ bool VRTSourcedRasterBand::CanUseSourcesMinMaxImplementations()
         {
             if (!((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') ||
                   (ch >= '0' && ch <= '9') || ch == ':' || ch == '/' ||
-                  ch == '\\' || ch == ' ' || ch == '.'))
+                  ch == '\\' || ch == ' ' || ch == '.' || ch == '_'))
                 break;
         }
         if (ch != '\0')
@@ -581,6 +616,15 @@ bool VRTSourcedRasterBand::CanUseSourcesMinMaxImplementations()
             VSIStatBuf sStat;
             if (VSIStat(pszFilename, &sStat) != 0)
                 return false;
+            if (nSources > 1)
+            {
+                struct CPLTimeVal tvCur;
+                CPLGettimeofday(&tvCur, nullptr);
+                if (tvCur.tv_sec - tvStart.tv_sec +
+                        (tvCur.tv_usec - tvStart.tv_usec) * 1e-6 >
+                    1)
+                    return false;
+            }
         }
     }
     return true;
@@ -623,6 +667,10 @@ double VRTSourcedRasterBand::GetMinimum(int *pbSuccess)
         return 0;
     }
 
+    struct CPLTimeVal tvStart;
+    memset(&tvStart, 0, sizeof(CPLTimeVal));
+    if (nSources > 1)
+        CPLGettimeofday(&tvStart, nullptr);
     double dfMin = 0;
     for (int iSource = 0; iSource < nSources; iSource++)
     {
@@ -636,7 +684,22 @@ double VRTSourcedRasterBand::GetMinimum(int *pbSuccess)
         }
 
         if (iSource == 0 || dfSourceMin < dfMin)
+        {
             dfMin = dfSourceMin;
+            if (dfMin == 0 && eDataType == GDT_Byte)
+                break;
+        }
+        if (nSources > 1)
+        {
+            struct CPLTimeVal tvCur;
+            CPLGettimeofday(&tvCur, nullptr);
+            if (tvCur.tv_sec - tvStart.tv_sec +
+                    (tvCur.tv_usec - tvStart.tv_usec) * 1e-6 >
+                1)
+            {
+                return GDALRasterBand::GetMinimum(pbSuccess);
+            }
+        }
     }
 
     if (pbSuccess != nullptr)
@@ -682,6 +745,10 @@ double VRTSourcedRasterBand::GetMaximum(int *pbSuccess)
         return 0;
     }
 
+    struct CPLTimeVal tvStart;
+    memset(&tvStart, 0, sizeof(CPLTimeVal));
+    if (nSources > 1)
+        CPLGettimeofday(&tvStart, nullptr);
     double dfMax = 0;
     for (int iSource = 0; iSource < nSources; iSource++)
     {
@@ -695,7 +762,22 @@ double VRTSourcedRasterBand::GetMaximum(int *pbSuccess)
         }
 
         if (iSource == 0 || dfSourceMax > dfMax)
+        {
             dfMax = dfSourceMax;
+            if (dfMax == 255.0 && eDataType == GDT_Byte)
+                break;
+        }
+        if (nSources > 1)
+        {
+            struct CPLTimeVal tvCur;
+            CPLGettimeofday(&tvCur, nullptr);
+            if (tvCur.tv_sec - tvStart.tv_sec +
+                    (tvCur.tv_usec - tvStart.tv_usec) * 1e-6 >
+                1)
+            {
+                return GDALRasterBand::GetMaximum(pbSuccess);
+            }
+        }
     }
 
     if (pbSuccess != nullptr)