From 92d6cd64c2fcda76324062539f86d8d3193d3136 Mon Sep 17 00:00:00 2001
From: Joey Kleingers <joey.kleingers@bluequartz.net>
Date: Mon, 23 Sep 2024 10:16:18 -0400
Subject: [PATCH] ENH: Update Read CSV Filter caching to handle modified files.
 (#1078)

* Adjust filter to re-read the headers from the header line every time.
* Adjust the filter to only re-read the file when the following occurs:

1. File path changes
2. File is modified
3. Headers mode is set to LINE and the header line has changed.

---------

Signed-off-by: Joey Kleingers <joey.kleingers@bluequartz.net>
---
 .../SimplnxCore/Filters/ReadCSVFileFilter.cpp | 97 +++++++++++--------
 1 file changed, 55 insertions(+), 42 deletions(-)

diff --git a/src/Plugins/SimplnxCore/src/SimplnxCore/Filters/ReadCSVFileFilter.cpp b/src/Plugins/SimplnxCore/src/SimplnxCore/Filters/ReadCSVFileFilter.cpp
index 61dc99c403..06f65f1ed5 100644
--- a/src/Plugins/SimplnxCore/src/SimplnxCore/Filters/ReadCSVFileFilter.cpp
+++ b/src/Plugins/SimplnxCore/src/SimplnxCore/Filters/ReadCSVFileFilter.cpp
@@ -38,6 +38,7 @@ struct ReadCSVFileFilterCache
   usize TotalLines = 0;
   usize HeadersLine = 0;
   std::string Headers;
+  fs::file_time_type LastModifiedTime;
 };
 
 std::atomic_int32_t s_InstanceId = 0;
@@ -323,6 +324,47 @@ IFilter::PreflightResult readHeaders(const std::string& inputFilePath, usize hea
   return {};
 }
 
+Result<> cacheHeaders(const ReadCSVData& readCsvData)
+{
+  std::fstream in(readCsvData.inputFilePath.c_str(), std::ios_base::in);
+  if(!in.is_open())
+  {
+    return MakeErrorResult(to_underlying(IssueCodes::FILE_NOT_OPEN), fmt::format("Could not open file for reading: {}", readCsvData.inputFilePath));
+  }
+
+  usize currentLine = 0;
+  while(!in.eof())
+  {
+    std::string line;
+    std::getline(in, line);
+    currentLine++;
+
+    if(currentLine == readCsvData.headersLine)
+    {
+      s_HeaderCache[s_InstanceId].Headers = line;
+      s_HeaderCache[s_InstanceId].HeadersLine = readCsvData.headersLine;
+      break;
+    }
+  }
+
+  return {};
+}
+
+Result<> cacheFullFile(const ReadCSVData& readCsvData)
+{
+  s_HeaderCache[s_InstanceId].FilePath = readCsvData.inputFilePath;
+  auto result = cacheHeaders(readCsvData);
+  if(result.invalid())
+  {
+    return result;
+  }
+
+  s_HeaderCache[s_InstanceId].TotalLines = nx::core::FileUtilities::LinesInFile(readCsvData.inputFilePath);
+  s_HeaderCache[s_InstanceId].LastModifiedTime = fs::last_write_time(readCsvData.inputFilePath);
+
+  return {};
+}
+
 } // namespace
 
 namespace nx::core
@@ -431,57 +473,28 @@ IFilter::PreflightResult ReadCSVFileFilter::preflightImpl(const DataStructure& d
   }
 
   StringVector headers;
-  if(readCSVData.inputFilePath != s_HeaderCache[s_InstanceId].FilePath)
+  auto lastModifiedTime = fs::last_write_time(readCSVData.inputFilePath);
+  if(readCSVData.inputFilePath != s_HeaderCache[s_InstanceId].FilePath || lastModifiedTime > s_HeaderCache[s_InstanceId].LastModifiedTime)
   {
-    int64 lineCount = nx::core::FileUtilities::LinesInFile(inputFilePath);
-    if(lineCount < 0)
-    {
-      return {MakeErrorResult<OutputActions>(to_underlying(IssueCodes::FILE_NOT_OPEN), fmt::format("Could not open file for reading: {}", inputFilePath)), {}};
-    }
-    std::fstream in(inputFilePath.c_str(), std::ios_base::in);
-    if(!in.is_open())
+    // File path changed or file was modified
+    auto result = cacheFullFile(readCSVData);
+    if(result.invalid())
     {
-      return {MakeErrorResult<OutputActions>(to_underlying(IssueCodes::FILE_NOT_OPEN), fmt::format("Could not open file for reading: {}", inputFilePath)), {}};
+      return {ConvertResultTo<OutputActions>(ConvertResult(std::move(result)), {})};
     }
-
-    s_HeaderCache[s_InstanceId].FilePath = readCSVData.inputFilePath;
-
-    usize currentLine = 0;
-    while(!in.eof())
-    {
-      std::string line;
-      std::getline(in, line);
-      currentLine++;
-
-      if(headerMode == ReadCSVData::HeaderMode::LINE && currentLine == readCSVData.headersLine)
-      {
-        s_HeaderCache[s_InstanceId].Headers = line;
-        s_HeaderCache[s_InstanceId].HeadersLine = readCSVData.headersLine;
-        break;
-      }
-    }
-
-    headers = StringUtilities::split(s_HeaderCache[s_InstanceId].Headers, readCSVData.delimiters, readCSVData.consecutiveDelimiters);
-    s_HeaderCache[s_InstanceId].TotalLines = lineCount;
   }
-  else if(headerMode == ReadCSVData::HeaderMode::LINE)
+  else if(headerMode == ReadCSVData::HeaderMode::LINE && readCSVData.headersLine != s_HeaderCache[s_InstanceId].HeadersLine)
   {
-    if(readCSVData.headersLine != s_HeaderCache[s_InstanceId].HeadersLine)
+    // We are in header line mode and the header line number changed
+    auto result = cacheHeaders(readCSVData);
+    if(result.invalid())
     {
-      IFilter::PreflightResult result = readHeaders(readCSVData.inputFilePath, readCSVData.headersLine, s_HeaderCache[s_InstanceId]);
-      if(result.outputActions.invalid())
-      {
-        return result;
-      }
+      return {ConvertResultTo<OutputActions>(ConvertResult(std::move(result)), {})};
     }
-
-    headers = StringUtilities::split(s_HeaderCache[s_InstanceId].Headers, readCSVData.delimiters, readCSVData.consecutiveDelimiters);
   }
 
-  if(headerMode == ReadCSVData::HeaderMode::CUSTOM)
-  {
-    headers = readCSVData.customHeaders;
-  }
+  headers = (headerMode == ReadCSVData::HeaderMode::LINE) ? StringUtilities::split(s_HeaderCache[s_InstanceId].Headers, readCSVData.delimiters, readCSVData.consecutiveDelimiters) :
+                                                            readCSVData.customHeaders;
 
   usize totalLines = s_HeaderCache[s_InstanceId].TotalLines;