This program does test reads and writes to a file.

file-soak-test.cpp

//Reading and writing tests
//Release under CC0 by Tim Sheerman-Chase, 2014

#include <stdio.h>
#include <stdlib.h>
#include <vector>
#include <list>
#include <iostream>
#include <string>
using namespace std;

int main(int argc, char **argv)
{
	
	FILE *fi = fopen("soaktest-cpp.dat", "w+b");

	int globalRandSeed = 0;
	srand(globalRandSeed);
	int numBins = 1000;

	cout << "Generate bin sizes" << endl;
	vector<unsigned> binSizes;
	int total = 0;
	for(unsigned i=0;i<numBins;i++)
	{
		int s = rand()%500001;
		binSizes.push_back(s);
		total += s;
	}

	cout << "Total test size " << total << endl;

	vector<unsigned> binOffsets;
	binOffsets.push_back(0);

	for(int i=0; i< binSizes.size()-1;i++)
	{
		unsigned val = binOffsets[binOffsets.size()-1]+binSizes[i];
		binOffsets.push_back(val);
	}

	vector<string> oldData;
	int oldSeed;

	while(1)
	{
		cout << "Begin iteration "<< globalRandSeed<< endl;
		globalRandSeed += 1;
		srand(globalRandSeed);

		//Generate new data
		vector<string> data;
		for(int i=0; i < binSizes.size();i++)
		{
			string tmp;
			for(int j=0;j<binSizes[i];j++)
			{
				tmp.append(1, (char)(rand()%256));
			}
			data.push_back(tmp);
			//cout << tmp.size() << "," << binSizes[i] << endl;
		}

		//Generate write order
		list<unsigned> accessOrder;
		for(int i=0; i < binSizes.size();i++)
		{
			accessOrder.push_back(i);
		}
		
		vector<unsigned> accessOrderShuffled;
		while(accessOrder.size())
		{
			unsigned ind = rand() % accessOrder.size();
			list<unsigned>::iterator it = accessOrder.begin();
			for(int i=0;i<ind;i++)
				it ++;
			accessOrderShuffled.push_back(*it);
			accessOrder.erase(it);
		}

		for(unsigned int i=0; i < accessOrderShuffled.size(); i++)
		{
			unsigned binNum = accessOrderShuffled[i];
			if(oldData.size()>0)
			{
				fseek(fi, binOffsets[binNum], SEEK_SET);
				char buff[500000];
				int readsize = fread(buff, 1, binSizes[binNum], fi);
				
				int checkok = 1;
				if(readsize!=binSizes[binNum])
					checkok = 0;
				int countMatch = 0;
				for(int j=0;j< readsize;j++)
					if(oldData[binNum].c_str()[j] == buff[j])
						countMatch += 1;
				if(countMatch != binSizes[binNum])
					checkok = 0;

				if (!checkok)
				{
					cout << "Readback failed." << endl;
					cout << binSizes[binNum] << "," << readsize << "," << countMatch << endl;

					cout << "expected:";
					for (int j=0;j<30;j++)
						cout << ((int)(oldData[binNum].c_str()[j])) << ",";
					cout << endl;

					cout << "got     :";
					for (int j=0;j<30;j++)
						cout << ((int)(buff[j])) << ",";
					cout << endl;

					exit(0);
				}
			}
			
			fseek(fi, binOffsets[binNum], SEEK_SET);
			fwrite(data[binNum].c_str(), 1, data[binNum].size(), fi);
		}

		//Flush every tenth interation to see if it makes a difference
		if(globalRandSeed % 10 == 0)
		{
			cout << "Flushing" << endl;
			fflush(fi);
		}

		oldData = data;
		oldSeed = globalRandSeed;
	}


}