42426 - nsPersistentProperties::Load() is too slow.

Status: VERIFIED INVALID

(Core :: XPCOM, defect, P3)

Description

[Patrick C. Beard]

With the recent string changes, I have a 256K .properties file that loads in 45 
seconds on my 400MHz Mac G3. This is unacceptable. The following patch fixes that 
(although perhaps not in the most ideal way):

Index: mozilla/xpcom/ds/nsPersistentProperties.cpp
===================================================================
RCS file: /cvsroot/mozilla/xpcom/ds/nsPersistentProperties.cpp,v
retrieving revision 1.8
diff -c -2 -r1.8 nsPersistentProperties.cpp
*** nsPersistentProperties.cpp	2000/05/26 20:59:04	1.8
--- nsPersistentProperties.cpp	2000/06/14 01:02:39
***************
*** 109,112 ****
--- 109,113 ----
      return NS_ERROR_FAILURE;
    }
+   nsAutoString key, value, oldValue;
    c = Read();
    while (1) {
***************
*** 120,125 ****
      }
      else {
!       nsAutoString key;
        while ((c >= 0) && (c != '=') && (c != ':')) {
          key.Append((PRUnichar) c);
          c = Read();
--- 121,128 ----
      }
      else {
!       key.Truncate(0);
        while ((c >= 0) && (c != '=') && (c != ':')) {
+         if (key.mCapacity == key.mLength)
+           key.SetCapacity(key.mCapacity * 2);
          key.Append((PRUnichar) c);
          c = Read();
***************
*** 131,135 ****
        key.Trim(trimThese, PR_FALSE, PR_TRUE);
        c = Read();
!       nsAutoString value;
        while ((c >= 0) && (c != '\r') && (c != '\n')) {
          if (c == '\\') {
--- 134,138 ----
        key.Trim(trimThese, PR_FALSE, PR_TRUE);
        c = Read();
!       value.Truncate(0);
        while ((c >= 0) && (c != '\r') && (c != '\n')) {
          if (c == '\\') {
***************
*** 139,150 ****
            }
            else {
              value.AppendWithConversion('\\');
            }
          }
          value.Append((PRUnichar) c);
          c = Read();
        }
        value.Trim(trimThese, PR_TRUE, PR_TRUE);
-       nsAutoString oldValue;
        mSubclass->SetStringProperty(key, value, oldValue);
      }
--- 142,156 ----
            }
            else {
+             if (value.mCapacity == value.mLength)
+               value.SetCapacity(value.mCapacity * 2);
              value.AppendWithConversion('\\');
            }
          }
+         if (value.mCapacity == value.mLength)
+           value.SetCapacity(value.mCapacity * 2);
          value.Append((PRUnichar) c);
          c = Read();
        }
        value.Trim(trimThese, PR_TRUE, PR_TRUE);
        mSubclass->SetStringProperty(key, value, oldValue);
      }

Comment 1

[Patrick C. Beard]

I tried rewriting the original algoritm, using a more sensible buffering 
strategy, but had difficulty getting the same results.

Comment 2

[Scott Collins]

string allocation policy has reverted to its original form, so I'm marking this 
bug as invalid (after all, it's not fixed, it's just restored to its original 
state).

Comment 3

[leger]

marking Verified per scc comment.