Skip to content
Entropy Documentation

EntropyEngine::Networking::SharedMemory::SharedMemoryControlBlock

EntropyEngine::Networking::SharedMemory::SharedMemoryControlBlock

Section titled “EntropyEngine::Networking::SharedMemory::SharedMemoryControlBlock”

Control block structure placed at the start of each shared memory region. More…

#include <SharedMemoryPlatform.h>

Public Functions

Section titled “Public Functions”
Name
boolvalidate() const
Validate control block was initialized correctly.
voidinitializeServer(size_t regionSize)
Initialize control block for server.

Public Attributes

Section titled “Public Attributes”
Name
uint32_tversion
Must be <= SHM_VERSION.
uint64_tvalidationToken
Random token for connection validation.
uint64_ttotalSize
Total region size.
std::atomic< uint32_t >shutdown
Shutdown requested.
std::atomic< uint32_t >serverReady
Server has initialized region.
uint32_tserverPid
Server process ID.
std::atomic< uint64_t >s2cWritePos
Server write position.
std::atomic< uint32_t >s2cWakeFlag
Wake flag for client.
std::atomic< uint64_t >s2cReadPos
Client read position.
uint64_tringBufferSize
Size of each ring buffer.
uint32_treserved2
Reserved for alignment.
uint32_treserved1
Reserved for alignment.
uint32_treserved0
Reserved for alignment.
uint8_t[40]padding2
Pad to 64 bytes.
uint8_t[40]padding1
Pad to 64 bytes.
uint8_t[24]padding0
Pad to 64 bytes.
uint32_tmagic
Must be SHM_MAGIC.
std::atomic< uint32_t >clientReady
Client has connected.
uint32_tclientPid
Client process ID (set after connect).
std::atomic< uint64_t >c2sWritePos
Client write position.
std::atomic< uint32_t >c2sWakeFlag
Wake flag for server.
std::atomic< uint64_t >c2sReadPos
Server read position.

Detailed Description

Section titled “Detailed Description”
struct EntropyEngine::Networking::SharedMemory::SharedMemoryControlBlock;

Control block structure placed at the start of each shared memory region.

Layout is fixed and must match across all platforms. Structure is organized into cache lines to prevent false sharing:

Cache line 0 [0-63]: Header + connection state (read-mostly) Cache line 1 [64-127]: Server-to-Client ring buffer atomics Cache line 2 [128-191]: Client-to-Server ring buffer atomics Cache line 3 [192-255]: Reserved for future use

Public Functions Documentation

Section titled “Public Functions Documentation”

function validate

Section titled “function validate”
inline bool validate() const

Validate control block was initialized correctly.

Return: true if magic and version are valid

function initializeServer

Section titled “function initializeServer”
inline void initializeServer(
    size_t regionSize
)

Initialize control block for server.

Parameters:

  • regionSize Total size of the shared memory region

Public Attributes Documentation

Section titled “Public Attributes Documentation”

variable version

Section titled “variable version”
uint32_t version;

Must be <= SHM_VERSION.

variable validationToken

Section titled “variable validationToken”
uint64_t validationToken;

Random token for connection validation.

variable totalSize

Section titled “variable totalSize”
uint64_t totalSize;

Total region size.

variable shutdown

Section titled “variable shutdown”
std::atomic< uint32_t > shutdown;

Shutdown requested.

variable serverReady

Section titled “variable serverReady”
std::atomic< uint32_t > serverReady;

Server has initialized region.

variable serverPid

Section titled “variable serverPid”
uint32_t serverPid;

Server process ID.

variable s2cWritePos

Section titled “variable s2cWritePos”
std::atomic< uint64_t > s2cWritePos;

Server write position.

variable s2cWakeFlag

Section titled “variable s2cWakeFlag”
std::atomic< uint32_t > s2cWakeFlag;

Wake flag for client.

variable s2cReadPos

Section titled “variable s2cReadPos”
std::atomic< uint64_t > s2cReadPos;

Client read position.

variable ringBufferSize

Section titled “variable ringBufferSize”
uint64_t ringBufferSize;

Size of each ring buffer.

variable reserved2

Section titled “variable reserved2”
uint32_t reserved2;

Reserved for alignment.

variable reserved1

Section titled “variable reserved1”
uint32_t reserved1;

Reserved for alignment.

variable reserved0

Section titled “variable reserved0”
uint32_t reserved0;

Reserved for alignment.

variable padding2

Section titled “variable padding2”
uint8_t[40] padding2;

Pad to 64 bytes.

variable padding1

Section titled “variable padding1”
uint8_t[40] padding1;

Pad to 64 bytes.

variable padding0

Section titled “variable padding0”
uint8_t[24] padding0;

Pad to 64 bytes.

variable magic

Section titled “variable magic”
uint32_t magic;

Must be SHM_MAGIC.

variable clientReady

Section titled “variable clientReady”
std::atomic< uint32_t > clientReady;

Client has connected.

variable clientPid

Section titled “variable clientPid”
uint32_t clientPid;

Client process ID (set after connect).

variable c2sWritePos

Section titled “variable c2sWritePos”
std::atomic< uint64_t > c2sWritePos;

Client write position.

variable c2sWakeFlag

Section titled “variable c2sWakeFlag”
std::atomic< uint32_t > c2sWakeFlag;

Wake flag for server.

variable c2sReadPos

Section titled “variable c2sReadPos”
std::atomic< uint64_t > c2sReadPos;

Server read position.

Updated on 2026-01-26 at 17:14:35 -0500