Stream View

.OpenStream() opens a Stream view to IMemory.

// Create memory
IMemory<byte> memory = new BlockMemory<byte>().RWLocked();
// Open a 'stream' view to 'memory'
using Stream stream = memory.OpenStream();

.OpenStream(fileAccess, fileShare) allows to configure file accesses.

// Open a 'stream' view to 'memory'
using Stream stream = memory.OpenStream(FileAccess.ReadWrite, FileShare.ReadWrite);

Multiple streams can be opened, however FileShare specifies exclusion policy.

try
{
    // Create memory
    IMemory<byte> memory = new BlockMemory<byte>();
    // Open two streams with write share exclusion
    using Stream stream1 = memory.OpenStream(FileAccess.ReadWrite, FileShare.Write);
    using Stream stream2 = memory.OpenStream(FileAccess.ReadWrite, FileShare.Write);
}
catch (IOException)
{
    // 'FileShare.Write' excludes the other read access request
}

FileShare Exclusion

.OpenStream() handles FileShare exclusion automatically.

However, explicit an openHandles context can be provided for share exclusion checks.

// Create memory
IMemory<byte> memory = new BlockMemory<byte>();
// List of open handle context for share exclusion properties
List<IFileAccess> openHandles = new();
// Open a 'stream' view to 'memory'
using var stream = new MemoryViewStream(memory, FileAccess.ReadWrite, FileShare.Write);
// Assert-and-write exclusion
FileShareContext.Instance.AddToFileShareContext(stream, openHandles);

FileShareContext.Instance.Provider provides shared openHandles context. It uses weak-keyed mapping.

// Create memory
IMemory<byte> memory = new BlockMemory<byte>();
// Create open handle context for 'memory' using weak-keyed-mapping
List<IFileAccess> openHandles = FileShareContext.Instance.Provider[memory];
// Open a 'stream' view to 'memory'
using var stream = new MemoryViewStream(memory, FileAccess.ReadWrite, FileShare.Write);
// Assert-and-write exclusion
FileShareContext.Instance.AddToFileShareContext(stream, openHandles);

Full Example

Full example

using Avalanche.Memory;
using Avalanche.Utilities;
using static System.Console;

public class streamview
{
    public static void Run()
    {
        {
            // <01>
            // Create memory
            IMemory<byte> memory = new BlockMemory<byte>().RWLocked();
            // Open a 'stream' view to 'memory'
            using Stream stream = memory.OpenStream();
            // </01>
        }
        {
            // Create memory
            IMemory<byte> memory = new BlockMemory<byte>();
            // <02>
            // Open a 'stream' view to 'memory'
            using Stream stream = memory.OpenStream(FileAccess.ReadWrite, FileShare.ReadWrite);
            // </02>
        }
        // <03>
        try
        {
            // Create memory
            IMemory<byte> memory = new BlockMemory<byte>();
            // Open two streams with write share exclusion
            using Stream stream1 = memory.OpenStream(FileAccess.ReadWrite, FileShare.Write);
            using Stream stream2 = memory.OpenStream(FileAccess.ReadWrite, FileShare.Write);
        }
        catch (IOException)
        {
            // 'FileShare.Write' excludes the other read access request
        }
        // </03>
        {
            // <04>
            // Create memory
            IMemory<byte> memory = new BlockMemory<byte>();
            // List of open handle context for share exclusion properties
            List<IFileAccess> openHandles = new();
            // Open a 'stream' view to 'memory'
            using var stream = new MemoryViewStream(memory, FileAccess.ReadWrite, FileShare.Write);
            // Assert-and-write exclusion
            FileShareContext.Instance.AddToFileShareContext(stream, openHandles);
            // </04>
        }
        {
            // <05>
            // Create memory
            IMemory<byte> memory = new BlockMemory<byte>();
            // Create open handle context for 'memory' using weak-keyed-mapping
            List<IFileAccess> openHandles = FileShareContext.Instance.Provider[memory];
            // Open a 'stream' view to 'memory'
            using var stream = new MemoryViewStream(memory, FileAccess.ReadWrite, FileShare.Write);
            // Assert-and-write exclusion
            FileShareContext.Instance.AddToFileShareContext(stream, openHandles);
            // </05>
        }
    }
}