Checkpointing additions to Cache

CMakeLists.txt

@@ -27,6 +27,7 @@ set(storagemanager_SRCS
     src/Cache.cpp
     src/SMLogging.cpp
     src/Downloader.cpp
+    src/Synchronizer.cpp
 )
 
 option(TRACE "Enable some tracing output" OFF)

src/Cache.cpp

@@ -6,6 +6,9 @@
 #include <syslog.h>
 #include <boost/filesystem.hpp>
 #include <boost/thread.hpp>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 using namespace std;
 using namespace boost::filesystem;
@@ -13,33 +16,52 @@ using namespace boost::filesystem;
 namespace storagemanager
 {
 
-Cache::Cache()
+Cache::Cache() : currentCacheSize(0)
 {
     Config *conf = Config::get();
+    logger = SMLogging::get();
+    sync = Synchronizer::get();
     
-    string ssize = conf->getValue("Cache", "cache_size");
-    if (ssize.empty()) 
+    string stmp = conf->getValue("Cache", "cache_size");
+    if (stmp.empty()) 
     {
-        syslog(LOG_CRIT, "Cache/cache_size is not set");
+        logger->log(LOG_CRIT, "Cache/cache_size is not set");
         throw runtime_error("Please set Cache/cache_size in the storagemanager.cnf file");
     }
     try
     {
-        maxCacheSize = stol(ssize);
+        maxCacheSize = stoul(stmp);
     }
     catch (invalid_argument &)
     {
-        syslog(LOG_CRIT, "Cache/cache_size is not a number");
+        logger->log(LOG_CRIT, "Cache/cache_size is not a number");
         throw runtime_error("Please set Cache/cache_size to a number");
     }
     //cout << "Cache got cache size " << maxCacheSize << endl;
         
+    stmp = conf->getValue("ObjectStorage", "object_size");
+    if (stmp.empty()) 
+    {
+        logger->log(LOG_CRIT, "ObjectStorage/object_size is not set");
+        throw runtime_error("Please set ObjectStorage/object_size in the storagemanager.cnf file");
+    }
+    try
+    {
+        objectSize = stoul(stmp);
+    }
+    catch (invalid_argument &)
+    {
+        logger->log(LOG_CRIT, "ObjectStorage/object_size is not a number");
+        throw runtime_error("Please set ObjectStorage/object_size to a number");
+    }
+    
     prefix = conf->getValue("Cache", "path");
     if (prefix.empty())
     {
-        syslog(LOG_CRIT, "Cache/path is not set");
+        logger->log(LOG_CRIT, "Cache/path is not set");
         throw runtime_error("Please set Cache/path in the storagemanager.cnf file");
     }
+    
     try 
     {
         boost::filesystem::create_directories(prefix);
@@ -82,6 +104,11 @@ void Cache::read(const vector<string> &keys)
             // not in the cache, put it in the list to download
             keysToFetch.push_back(&key);
     }
+    
+    // TODO: get the sizes of the objects to download and make space
+    // For now using an estimate
+    makeSpace(keys.size() * objectSize);
+    
     s.unlock();
     
     // start downloading the keys to fetch
@@ -154,6 +181,10 @@ const boost::filesystem::path & Cache::getCachePath()
         
 void Cache::exists(const vector<string> &keys, vector<bool> *out)
 {
+    out->resize(keys.size());
+    boost::unique_lock<boost::mutex> s(lru_mutex);
+    for (int i = 0; i < keys.size(); i++)
+        (*out)[i] = (m_lru.find(keys[i]) == m_lru.end());
 }
 
 void Cache::newObject(const string &key, size_t size)
@@ -164,12 +195,51 @@ void Cache::deletedObject(const string &key, size_t size)
 {
 }
 
-void Cache::setCacheSize(size_t size)
+void Cache::setMaxCacheSize(size_t size)
 {
 }
 
+// call this holding lru_mutex
 void Cache::makeSpace(size_t size)
 {
+    ssize_t thisMuch = currentCacheSize + size - maxCacheSize;
+    if (thisMuch <= 0)
+        return;
+
+    struct stat statbuf;
+    LRU_t::iterator it = lru.begin();
+    while (it != lru.end() && thisMuch > 0)
+    {
+        if (doNotEvict.find(it) != doNotEvict.end())
+        {
+            ++it;
+            continue;   // it's in the do-not-evict list
+        }
+        
+        boost::filesystem::path cachedFile = prefix / *it;
+        int err = stat(cachedFile.string().c_str(), &statbuf);
+        if (err)
+        {
+            logger->log(LOG_WARNING, "Downloader: There seems to be a cached file that couldn't be stat'ed: %s", cachedFile.string().c_str());
+            ++it;
+            continue;
+        }
+        
+        /* 
+            TODO: tell Synchronizer that this key will be evicted
+            delete the file
+            remove it from our structs
+            update current size
+        */
+        assert(currentCacheSize >= statbuf.st_size);
+        currentCacheSize -= statbuf.st_size;
+        thisMuch -= statbuf.st_size;
+        sync->flushObject(*it);
+        boost::filesystem::remove(cachedFile);
+        LRU_t::iterator toRemove = it++;
+        lru.erase(toRemove);
+        m_lru.erase(*toRemove);
+    }
 }
 
 

src/Cache.h

@@ -3,6 +3,8 @@
 #define CACHE_H_
 
 #include "Downloader.h"
+#include "SMLogging.h"
+#include "Synchronizer.h"
 
 #include <string>
 #include <vector>
@@ -25,14 +27,21 @@ class Cache : public boost::noncopyable
         void exists(const std::vector<std::string> &keys, std::vector<bool> *out);
         void newObject(const std::string &key, size_t size);
         void deletedObject(const std::string &key, size_t size);
-        void setCacheSize(size_t size);
-        void makeSpace(size_t size);
+        void setMaxCacheSize(size_t size);
+        size_t getCurrentCacheSize();
         
         // test helpers
         const boost::filesystem::path &getCachePath();
     private:
         boost::filesystem::path prefix;
         size_t maxCacheSize;
+        size_t objectSize;
+        size_t currentCacheSize;
+        Downloader downloader;
+        Synchronizer *sync;
+        SMLogging *logger;
+        
+        void makeSpace(size_t size);
 
         /* The main cache structures */
         // lru owns the string memory for the filenames it manages.  m_lru and DNE point to those strings.
@@ -83,9 +92,6 @@ class Cache : public boost::noncopyable
         void addToDNE(const LRU_t::iterator &key);
         void removeFromDNE(const LRU_t::iterator &key);
         boost::mutex lru_mutex;   // protects the main cache structures & the do-not-evict set
-        
-        Downloader downloader;
-        
 };
 
 

src/CloudStorage.cpp

@@ -13,7 +13,7 @@ using namespace std;
 namespace
 {
     boost::mutex m;
-    storagemanager::CloudStorage *inst;
+    storagemanager::CloudStorage *inst = NULL;
     
 string tolower(const string &s)
 {
@@ -29,10 +29,10 @@ namespace storagemanager
 {
 CloudStorage * CloudStorage::get()
 {
-    SMLogging* logger = SMLogging::get();
     if (inst)
         return inst;
     
+    SMLogging* logger = SMLogging::get();
     Config *conf = Config::get();
     string type = tolower(conf->getValue("ObjectStorage", "service"));
     boost::mutex::scoped_lock s(m);

src/Config.h

@@ -3,12 +3,12 @@
 #define CONFIG_H_
 
 #include <boost/property_tree/ptree.hpp>
-//#include <boost/thread/mutex.hpp>
 #include <boost/thread.hpp>
 #include <sys/types.h>
 
 #include <string>
 
+/* TODO.  Need a config change listener impl. */
 
 namespace storagemanager
 {

src/Downloader.cpp

@@ -1,5 +1,6 @@
 #include "Downloader.h"
 #include "Config.h"
+#include "SMLogging.h"
 #include <string>
 #include <errno.h>
 #include <iostream>
@@ -18,11 +19,12 @@ Downloader::Downloader() : maxDownloads(0)
     }
     catch(invalid_argument)
     {
-        // log something
+        logger->log(LOG_WARNING, "Downloader: Invalid arg for ObjectStorage/max_concurrent_downloads, using default of 20");
     }
     if (maxDownloads == 0)
         maxDownloads = 20;
     workers.reset(new ThreadPool(maxDownloads));
+    logger = SMLogging::get();
 }
 
 Downloader::~Downloader()
@@ -92,9 +94,13 @@ int Downloader::download(const vector<const string *> &keys, vector<int> *errnos
         auto &dl = dls[i];
         (*errnos)[i] = dl->dl_errno;
         if (dl->dl_errno != 0)
+        {
+            char buf[80];
+            logger->log(LOG_ERR, "Downloader: failed to download %s, got %s", keys[i]->c_str(), strerror_r(dl->dl_errno, buf, 80));
             ret = -1;
         }
     }
+}
 
 void Downloader::setDownloadPath(const string &path)
 {

src/Downloader.h

@@ -3,6 +3,7 @@
 
 #include "ThreadPool.h"
 #include "CloudStorage.h"
+#include "SMLogging.h"
 #include <unordered_set>
 #include <vector>
 #include <string>
@@ -68,6 +69,7 @@ class Downloader
         boost::mutex &getDownloadMutex();
         boost::scoped_ptr<ThreadPool> workers;
         CloudStorage *storage;
+        SMLogging *logger;
 };
 
 }

src/Synchronizer.cpp

@@ -0,0 +1,40 @@
+
+#include "Synchronizer.h"
+#include <boost/thread/mutex.hpp>
+
+using namespace std;
+
+namespace
+{
+    storagemanager::Synchronizer *instance = NULL;
+    boost::mutex inst_mutex;
+}
+
+
+namespace storagemanager
+{
+
+Synchronizer * Synchronizer::get()
+{
+    if (instance)
+        return instance;
+    boost::unique_lock<boost::mutex> lock(inst_mutex);
+    if (instance)
+        return instance;
+    instance = new Synchronizer();
+    return instance;
+}
+
+Synchronizer::Synchronizer()
+{
+}
+
+Synchronizer::~Synchronizer()
+{
+}
+
+void Synchronizer::flushObject(const string &key)
+{
+}
+
+}

src/Synchronizer.h

@@ -0,0 +1,24 @@
+
+#ifndef SYNCHRONIZER_H_
+#define SYNCHRONIZER_H_
+
+#include <string>
+#include <boost/utility.hpp>
+
+namespace storagemanager
+{
+
+class Synchronizer : public boost::noncopyable
+{
+    public:
+        static Synchronizer *get();
+        virtual ~Synchronizer();
+        
+        void flushObject(const std::string &key);
+
+    private:
+        Synchronizer();
+};
+
+}
+#endif