Limit the number of vector values printed with printCompact

Summary:
When printing out records, in particular with vector-vrs, we can have huge vectors of values, with many million values. Printing them out in a terminal makes the whole feature basically useless.
This diff limits the number of vector values printed out to 400.

Differential Revision: D54401272

fbshipit-source-id: d8899528e3f46e75c81bf008b6cce64829e09950

vrs/DataLayout.cpp

@@ -1141,6 +1141,9 @@ size_t getCountPerLine(const T& value) {
   ss << FORMAT(value, ss);
   return max<size_t>(1, 96 / (ss.str().size() + 1));
 }
+
+const size_t kPrintCompactMaxVectorValues = 400; // arbitrary
+
 } // namespace
 
 template <typename T>
@@ -1369,7 +1372,7 @@ void DataPieceVector<T>::printCompact(ostream& out, const string& indent) const
   vector<T> values;
   get(values);
   const size_t kCountPerLine = values.empty() ? 1 : getCountPerLine<T>(values.front());
-  for (size_t k = 0; k < values.size(); k++) {
+  for (size_t k = 0; k < min<size_t>(kPrintCompactMaxVectorValues, values.size()); k++) {
     if (k % kCountPerLine == 0 && values.size() > kCountPerLine) {
       out << "\n" << indent << "    ";
     } else {
@@ -1378,6 +1381,11 @@ void DataPieceVector<T>::printCompact(ostream& out, const string& indent) const
     using namespace special_chars;
     out << FORMAT(values[k], out);
   }
+  if (values.size() > kPrintCompactMaxVectorValues) {
+    out << "\n"
+        << indent << "    ...and " << values.size() - kPrintCompactMaxVectorValues
+        << " more values.";
+  }
   if (getOffset() == DataLayout::kNotFound) {
     out << "<unavailable>";
   }
@@ -1390,14 +1398,19 @@ void DataPieceVector<string>::printCompact(ostream& out, const string& indent) c
   out << indent << getLabel() << ": ";
   vector<string> values;
   get(values);
-  for (size_t k = 0; k < values.size(); k++) {
+  for (size_t k = 0; k < min<size_t>(kPrintCompactMaxVectorValues, values.size()); k++) {
     if (k % kCountPerLine == 0 && values.size() > kCountPerLine) {
       out << "\n" << indent << "    ";
     } else {
       out << ' ';
     }
     out << '"' << compactString(values[k]) << '"';
   }
+  if (values.size() > kPrintCompactMaxVectorValues) {
+    out << "\n"
+        << indent << "    ...and " << values.size() - kPrintCompactMaxVectorValues
+        << " more values.";
+  }
   if (getOffset() == DataLayout::kNotFound) {
     out << "<unavailable>";
   }

vrs/DataPieces.h

@@ -21,7 +21,6 @@
 
 #include <cstring>
 
-#include <algorithm>
 #include <map>
 #include <ostream>