From 30fc7b8d043c85a6d65b0bad0edf48a75e3f95b1 Mon Sep 17 00:00:00 2001
From: Kolyvan <ru.kolyvan@gmail.com>
Date: Fri, 8 Jan 2016 15:01:14 +1000
Subject: [PATCH] tune the buffer size for reading file

---
 KxSMBProvider.m                  | 15 +++++++++++----
 KxSMBSample/FileViewController.m |  2 +-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/KxSMBProvider.m b/KxSMBProvider.m
index 18a9c9d..7b8c85d 100644
--- a/KxSMBProvider.m
+++ b/KxSMBProvider.m
@@ -2158,8 +2158,13 @@ - (id)readDataOfLength:(NSUInteger)length
         NSError *error = [self openFile];
         if (error) return error;        
     }
-        
-    Byte buffer[32768];
+    
+    // it seems 512 kb is an optimal buffer size
+    const size_t bufferSize = MIN(length, 512*1024);
+    Byte *buffer = malloc(bufferSize);
+    if (!buffer) {
+        return mkKxSMBError(KxSMBErrorOutOfMemory, nil);
+    }
     
     smbc_read_fn readFn = smbc_getFunctionRead(_context);
     NSMutableData *md = [NSMutableData data];
@@ -2167,7 +2172,7 @@ - (id)readDataOfLength:(NSUInteger)length
     
     while (bytesToRead > 0) {
         
-        ssize_t r = readFn(_context, _file, buffer, MIN(bytesToRead, sizeof(buffer)));
+        ssize_t r = readFn(_context, _file, buffer, MIN(bytesToRead, bufferSize));
         
         if (r == 0)
             break;
@@ -2175,6 +2180,7 @@ - (id)readDataOfLength:(NSUInteger)length
         if (r < 0) {
                         
             const int err = errno;
+            free(buffer);
             return mkKxSMBError(errnoToSMBErr(err),
                                 NSLocalizedString(@"Unable read file:%@ (errno:%d)", nil), _path, err);
         }
@@ -2182,7 +2188,8 @@ - (id)readDataOfLength:(NSUInteger)length
         [md appendBytes:buffer length:r];
         bytesToRead -= r;
     }
-        
+    
+    free(buffer);
     return md;
 }
 
diff --git a/KxSMBSample/FileViewController.m b/KxSMBSample/FileViewController.m
index 05fc8c4..3a81fab 100644
--- a/KxSMBSample/FileViewController.m
+++ b/KxSMBSample/FileViewController.m
@@ -301,7 +301,7 @@ -(void) updateDownloadStatus: (id) result
 - (void) download
 {    
     __weak __typeof(self) weakSelf = self;
-    [_smbFile readDataOfLength:32768
+    [_smbFile readDataOfLength:1024*1024
                          block:^(id result)
     {
         FileViewController *p = weakSelf;