From 6e7b8f94bf7fdc087cd1eed604eabed6070dffad Mon Sep 17 00:00:00 2001
From: Jon Bergli Heier <snakebite@jvnv.net>
Date: Wed, 2 Mar 2011 19:22:33 +0100
Subject: Implemented simple caching for transcoded audio data.

---
 .gitignore |  3 +++
 SConstruct |  1 +
 cache.cpp  | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 cache.h    | 26 ++++++++++++++++++++++++++
 config.cpp |  1 +
 music.cpp  | 30 +++++++++++++-----------------
 6 files changed, 91 insertions(+), 17 deletions(-)
 create mode 100644 cache.cpp
 create mode 100644 cache.h

diff --git a/.gitignore b/.gitignore
index 85183e8..fc370ea 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,6 @@
 .sconsign.dblite
 .sconf_temp
 config.log
+/audist.db
+/static
+/cache
diff --git a/SConstruct b/SConstruct
index 6b960cf..65311ab 100644
--- a/SConstruct
+++ b/SConstruct
@@ -24,6 +24,7 @@ else:
 env.ParseConfig('pkg-config --cflags --libs libmpg123')
 env.ParseConfig('pkg-config --cflags --libs id3tag')
 env.ParseConfig('pkg-config --cflags --libs vorbisenc')
+env.ParseConfig('pkg-config --cflags --libs libssl')
 
 env.Program('audistd', Glob('*.cpp') + Glob('decoders/*.cpp') + Glob('encoders/*.cpp'))
 
diff --git a/cache.cpp b/cache.cpp
new file mode 100644
index 0000000..92e0cfa
--- /dev/null
+++ b/cache.cpp
@@ -0,0 +1,47 @@
+#include "cache.h"
+#include "config.h"
+
+#include <boost/format.hpp>
+#include <boost/filesystem/fstream.hpp>
+#include <openssl/sha.h>
+
+#include <iostream>
+#include <stdexcept>
+
+EncodedCache::EncodedCache(fs::path path, Decoder::p decoder, Encoder::p encoder) {
+	this->decoder = decoder;
+	this->encoder = encoder;
+
+	// TODO: Differentiate between encoders?
+	SHA_CTX context;
+	unsigned char md[SHA_DIGEST_LENGTH];
+	SHA_Init(&context);
+	SHA_Update(&context, (unsigned char*)path.string().c_str(), path.string().length());
+	SHA_Final(md, &context);
+	for(int i = 0; i < SHA_DIGEST_LENGTH; i++) {
+		hash = hash + (boost::format("%02x") % (int)md[i]).str();
+	}
+}
+
+fs::path EncodedCache::get_path() {
+	return fs::path(config::vm["audist.cache_dir"].as<std::string>()) / hash;
+}
+
+void EncodedCache::create_cache() {
+	fs::path path = get_path();
+
+	// TODO: Locking?
+	fs::ofstream os(path, std::ios::out | std::ios::binary);
+	// TODO: Make an encoder-to-istream adapter to get rid of this:
+
+	if(!os.is_open())
+		throw std::runtime_error("failed to create cache object");
+	char data[0x10000];
+	std::streamsize size = 1;
+	while(size) {
+		size = encoder->read(data, 0x10000);
+		if(size > 0)
+			os.write(data, size);
+	}
+	os.close();
+}
diff --git a/cache.h b/cache.h
new file mode 100644
index 0000000..21d4a52
--- /dev/null
+++ b/cache.h
@@ -0,0 +1,26 @@
+#ifndef CACHE_H
+#define CACHE_H
+
+#include "decoder.h"
+#include "encoder.h"
+
+#include <boost/filesystem.hpp>
+
+namespace fs = boost::filesystem;
+
+class EncodedCache {
+	private:
+		Decoder::p decoder;
+		Encoder::p encoder;
+
+		std::string hash;
+
+	public:
+		EncodedCache(fs::path path, Decoder::p decoder, Encoder::p encoder);
+		virtual ~EncodedCache() {};
+
+		fs::path get_path();
+		void create_cache();
+};
+
+#endif
diff --git a/config.cpp b/config.cpp
index 68e8a2f..910d0f0 100644
--- a/config.cpp
+++ b/config.cpp
@@ -14,6 +14,7 @@ void config::init() {
 		("audist.telnetd_port", po::value<int>()->default_value(7681), "telnetd port")
 		("audist.threads", po::value<std::size_t>()->default_value(10), "threads")
 		("audist.database", po::value<std::string>(), "database string")
+		("audist.cache_dir", po::value<std::string>(), "cache dir")
 	;
 	std::ifstream is("audist.conf", std::ios::in);
 	po::store(po::parse_config_file(is, desc, true), vm);
diff --git a/music.cpp b/music.cpp
index de5575f..51c44a8 100644
--- a/music.cpp
+++ b/music.cpp
@@ -2,8 +2,8 @@
 #include "decoder.h"
 #include "encoder.h"
 #include "tag.h"
-#include "config.h"
 #include "database.h"
+#include "cache.h"
 
 #include <boost/format.hpp>
 #include <boost/algorithm/string/predicate.hpp>
@@ -170,26 +170,22 @@ MusicDirectory::MusicDirectory(const fs::path root) {
 
 void MusicTrack::render(HTTP::Connection::p req) {
 	req->add_header("content-type", "application/octet-stream");
+	fs::path file_path = path;
 
 	if(req->args.count("decoder") && req->args.count("encoder")) {
 		Decoder::p decoder = Decoder::get(req->args["decoder"], path.string());
 		Encoder::p encoder = Encoder::get(req->args["encoder"], decoder);
-		
-		// TODO: Make an encoder-to-istream adapter to get rid of this:
-		char data[0x10000];
-		std::streamsize size = 1;
-		while(size) {
-			size = encoder->read(data, 0x10000);
-			if(size > 0)
-				req->send_data(data, size);
-		}
-		
-	} else {
-		fs::ifstream is(path, std::ios::in | std::ios::binary);
-		is.seekg(0, std::ios::end);
-		req->add_header("content-length", boost::str(boost::format("%d") % is.tellg()));
-		is.seekg(0, std::ios::beg);
 
-		req->send_data(is);
+		EncodedCache ec(path, decoder, encoder);
+		file_path = ec.get_path();
+		if(!fs::exists(file_path))
+			ec.create_cache();
 	}
+
+	fs::ifstream is(file_path, std::ios::in | std::ios::binary);
+	is.seekg(0, std::ios::end);
+	req->add_header("content-length", boost::str(boost::format("%d") % is.tellg()));
+	is.seekg(0, std::ios::beg);
+
+	req->send_data(is);
 }
-- 
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