From c98ed3b8b2da44182551ed8c996c7102b9fec113 Mon Sep 17 00:00:00 2001
From: Mohamed Omran <mohamed.omran@gmail.com>
Date: Fri, 29 Aug 2014 17:16:41 +0200
Subject: minor changes to variable names and error messages + set default
 backed in convert_mnist_data.cpp to lmdb

---
 examples/mnist/convert_mnist_data.cpp | 45 ++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 19 deletions(-)

(limited to 'examples/mnist')

diff --git a/examples/mnist/convert_mnist_data.cpp b/examples/mnist/convert_mnist_data.cpp
index 6fbd2943..0d3e91ec 100644
--- a/examples/mnist/convert_mnist_data.cpp
+++ b/examples/mnist/convert_mnist_data.cpp
@@ -2,7 +2,8 @@
 // This script converts the MNIST dataset to the leveldb format used
 // by caffe to perform classification.
 // Usage:
-//    convert_mnist_data input_image_file input_label_file output_db_file
+//    convert_mnist_data [FLAGS] input_image_file input_label_file
+//                        output_db_file
 // The MNIST dataset could be downloaded at
 //    http://yann.lecun.com/exdb/mnist/
 
@@ -20,7 +21,10 @@
 
 #include "caffe/proto/caffe.pb.h"
 
-DEFINE_string(backend, "leveldb", "The backend for storing the result");
+using namespace caffe;  // NOLINT(build/namespaces)
+using std::string;
+
+DEFINE_string(backend, "lmdb", "The backend for storing the result");
 
 uint32_t swap_endian(uint32_t val) {
     val = ((val << 8) & 0xFF00FF00) | ((val >> 8) & 0xFF00FF);
@@ -28,7 +32,7 @@ uint32_t swap_endian(uint32_t val) {
 }
 
 void convert_dataset(const char* image_filename, const char* label_filename,
-        const char* db_filename, const std::string& db_backend) {
+        const char* db_path, const string& db_backend) {
   // Open files
   std::ifstream image_file(image_filename, std::ios::in | std::ios::binary);
   std::ifstream label_file(label_filename, std::ios::in | std::ios::binary);
@@ -65,55 +69,58 @@ void convert_dataset(const char* image_filename, const char* label_filename,
   // leveldb
   leveldb::DB* db;
   leveldb::Options options;
-  options.create_if_missing = true;
   options.error_if_exists = true;
+  options.create_if_missing = true;
   options.write_buffer_size = 268435456;
   leveldb::WriteBatch* batch = NULL;
 
-  // Open new db
+  // Open db
   if (db_backend == "leveldb") {  // leveldb
+    LOG(INFO) << "Opening leveldb " << db_path;
     leveldb::Status status = leveldb::DB::Open(
-        options, db_filename, &db);
-    CHECK(status.ok()) << "Failed to open leveldb " << db_filename
+        options, db_path, &db);
+    CHECK(status.ok()) << "Failed to open leveldb " << db_path
         << ". Is it already existing?";
     batch = new leveldb::WriteBatch();
   } else if (db_backend == "lmdb") {  // lmdb
-    CHECK_EQ(mkdir(db_filename, 0744), 0)
-        << "mkdir " << db_filename << "failed";
+    LOG(INFO) << "Opening lmdb " << db_path;
+    CHECK_EQ(mkdir(db_path, 0744), 0)
+        << "mkdir " << db_path << "failed";
     CHECK_EQ(mdb_env_create(&mdb_env), MDB_SUCCESS) << "mdb_env_create failed";
     CHECK_EQ(mdb_env_set_mapsize(mdb_env, 1099511627776), MDB_SUCCESS)  // 1TB
         << "mdb_env_set_mapsize failed";
-    CHECK_EQ(mdb_env_open(mdb_env, db_filename, 0, 0664), MDB_SUCCESS)
+    CHECK_EQ(mdb_env_open(mdb_env, db_path, 0, 0664), MDB_SUCCESS)
         << "mdb_env_open failed";
     CHECK_EQ(mdb_txn_begin(mdb_env, NULL, 0, &mdb_txn), MDB_SUCCESS)
         << "mdb_txn_begin failed";
     CHECK_EQ(mdb_open(mdb_txn, NULL, 0, &mdb_dbi), MDB_SUCCESS)
-        << "mdb_open failed";
+        << "mdb_open failed. Does the lmdb already exist? ";
   } else {
     LOG(FATAL) << "Unknown db backend " << db_backend;
   }
 
+  // Storing to db
   char label;
   char* pixels = new char[rows * cols];
-  const int kMaxKeyLength = 10;
-  char key[kMaxKeyLength];
-  std::string value;
   int count = 0;
+  const int kMaxKeyLength = 10;
+  char key_cstr[kMaxKeyLength];
+  string value;
 
-  caffe::Datum datum;
+  Datum datum;
   datum.set_channels(1);
   datum.set_height(rows);
   datum.set_width(cols);
   LOG(INFO) << "A total of " << num_items << " items.";
   LOG(INFO) << "Rows: " << rows << " Cols: " << cols;
-  for (int itemid = 0; itemid < num_items; ++itemid) {
+  for (int item_id = 0; item_id < num_items; ++item_id) {
     image_file.read(pixels, rows * cols);
     label_file.read(&label, 1);
     datum.set_data(pixels, rows*cols);
     datum.set_label(label);
+    snprintf(key_cstr, kMaxKeyLength, "%08d", item_id);
     datum.SerializeToString(&value);
-    snprintf(key, kMaxKeyLength, "%08d", itemid);
-    std::string keystr(key);
+    string keystr(key_cstr);
 
     // Put in db
     if (db_backend == "leveldb") {  // leveldb
@@ -179,7 +186,7 @@ int main(int argc, char** argv) {
         "or directly use data/mnist/get_mnist.sh\n");
   gflags::ParseCommandLineFlags(&argc, &argv, true);
 
-  const std::string& db_backend = FLAGS_backend;
+  const string& db_backend = FLAGS_backend;
 
   if (argc != 4) {
     gflags::ShowUsageWithFlagsRestrict(argv[0],
-- 
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