RedisBuffer< T > Class Template Reference

Buffer implementation that stores and retrieves data from a Redis server using the Arduino Client. More...

#include <RedisBuffer.h>

Inheritance diagram for RedisBuffer< T >:

Classes
struct	RedisResult

Public Member Functions
	RedisBuffer (Client &client, const char *key, size_t max_size, size_t local_buf_size=512, int expire_seconds=60 *60)
	Constructs a RedisBuffer.
T *	address () override
	Returns the address of the start of the physical read buffer (not supported).
int	available () override
	Returns the number of elements available to read (local + Redis). Flushes any pending writes before checking.
int	availableForWrite () override
	Returns the number of elements that can be written before reaching max_size. There are are no checks in place that would prevent that the size values is exeeded: This is for information only!
void	clear ()
	same as reset
virtual int	clearArray (int len)
	Removes the next len entries.
bool	isEmpty ()
virtual bool	isFull ()
	checks if the buffer is full
virtual float	levelPercent ()
	Returns the level of the buffer in %.
bool	peek (T &result) override
	Peeks at the next value in Redis directly (no local buffer). Flushes any pending writes before peeking.
bool	read (T &result) override
	Reads a single value from Redis directly (no local buffer). Flushes any pending writes before reading.
int	readArray (T data[], int len) override
	Reads multiple values from the buffer in one batch. Flushes any pending writes before reading.
void	reset () override
	Clears the buffer both locally and on the Redis server. Flushes any pending writes before clearing.
bool	resize (int size) override
	Resizes the maximum buffer size. This operation is only allowed before any write has occurred.
void	setExpire (int seconds)
	Sets the expiration time (in seconds) for the Redis key. The expiration will be refreshed on every write/flush.
size_t	size () override
	Returns the maximum capacity of the buffer.
bool	write (T data) override
	Buffers a single value for writing to Redis. Data is only sent to Redis when the local buffer is full or writeArray is called.
int	writeArray (const T data[], int len) override
	Writes multiple values to Redis in one batch. Flushes any pending writes before sending the new data.
virtual int	writeArrayOverwrite (const T data[], int len)
	Fills the buffer data and overwrites the oldest data if the buffer is full.

Protected Member Functions
void	clearResponse ()
void	fillReadBuffer ()
	Fills the local read buffer from Redis using LRANGE. After reading, removes the items from Redis using LTRIM.
void	flushWrite ()
	Flushes buffered writes to Redis using RPUSH and sets expiration if configured.
RedisResult	readResponse ()
	Reads a single line response from the Redis server and parses it into a RedisResult.
String	redisCommand (const String &cmd, const String &arg1="", const String &arg2="", const String &arg3="")
	Constructs a Redis command in RESP format.
RedisResult	sendCommand (const String &cmd)
	Sends a command to the Redis server and returns the parsed result.

Protected Attributes
Client &	client
	Reference to the Arduino Client for Redis communication.
int	expire_seconds = 0
	Expiration time in seconds (0 = no expiration).
bool	has_written = false
	True if any write operation has occurred.
const char *	key
	Redis key for the buffer.
size_t	local_buf_size
	Local buffer size for batching.
size_t	max_size
	Maximum number of elements in the buffer.
SingleBuffer< T >	read_buf
	Local buffer for pending reads.
SingleBuffer< T >	write_buf
	Local buffer for pending writes.

Detailed Description

template<typename T>
class audio_tools::RedisBuffer< T >

Buffer implementation that stores and retrieves data from a Redis server using the Arduino Client.

This buffer uses a Redis list as a circular buffer and batches read/write operations for efficiency. Individual write/read calls are buffered locally using SingleBuffer and only sent to Redis in bulk when writeArray/readArray is called or when the buffer is full/empty. This reduces network overhead and improves performance for streaming scenarios.

• Uses RPUSH for writing and LPOP for reading from Redis.
• All Redis commands are constructed using the RESP protocol and sent via the Arduino Client API.
• The buffer size for local batching can be configured via the constructor.
• Supports automatic expiration of the Redis key after a specified number of seconds.

Template Parameters

T	Data type to buffer (e.g., uint8_t, int16_t)

Constructor & Destructor Documentation

RedisBuffer()

template<typename T >

RedisBuffer ( Client &  client, const char *  key, size_t  max_size, size_t  local_buf_size = 512, int  expire_seconds = 60 * 60  )

inline

Constructs a RedisBuffer.

Parameters

client	Reference to a connected Arduino Client (e.g., WiFiClient, EthernetClient).
key	Redis key to use for the buffer (list).
max_size	Maximum number of elements in the buffer.
local_buf_size	Size of the local buffer for batching (default: 512).
expire_seconds	Number of seconds after which the Redis key should expire (0 = no expiration).

Member Function Documentation

address()

template<typename T >

T * address ( )

inlineoverridevirtual

Returns the address of the start of the physical read buffer (not supported).

Returns

nullptr.

Implements BaseBuffer< T >.

available()

template<typename T >

int available ( )

inlineoverridevirtual

Returns the number of elements available to read (local + Redis). Flushes any pending writes before checking.

Returns

Number of available elements.

Implements BaseBuffer< T >.

availableForWrite()

template<typename T >

int availableForWrite ( )

inlineoverridevirtual

Returns the number of elements that can be written before reaching max_size. There are are no checks in place that would prevent that the size values is exeeded: This is for information only!

Returns

Number of available slots for writing.

Implements BaseBuffer< T >.

clearArray()

template<typename T >

virtual int clearArray ( int  len )

inlinevirtualinherited

Removes the next len entries.

Reimplemented in SingleBuffer< T >, SingleBuffer< float >, SingleBuffer< int16_t >, SingleBuffer< stsz_sample_size_t >, SingleBuffer< uint32_t >, and SingleBuffer< uint8_t >.

isFull()

template<typename T >

virtual bool isFull ( )

inlinevirtualinherited

checks if the buffer is full

Reimplemented in VariableSpeedRingBufferSimple< T >, VariableSpeedRingBuffer180< T >, VariableSpeedRingBuffer< T >, VariableSpeedRingBuffer< int16_t >, NBuffer< T >, NBuffer< Frame >, NBuffer< uint8_t >, BufferRP2040T< T >, BufferRTOS< T >, BufferRTOS< uint8_t >, SynchronizedBuffer< T >, SingleBuffer< T >, SingleBuffer< float >, SingleBuffer< int16_t >, SingleBuffer< stsz_sample_size_t >, SingleBuffer< uint32_t >, SingleBuffer< uint8_t >, RingBuffer< T >, RingBuffer< int16_t >, RingBuffer< Sample >, RingBuffer< uint16_t >, RingBuffer< uint8_t >, RingBufferFile< File, T >, and DynamicMultiBuffer< T, BufferType >.

peek()

template<typename T >

bool peek ( T &  result )

inlineoverridevirtual

Peeks at the next value in Redis directly (no local buffer). Flushes any pending writes before peeking.

Parameters

result

Reference to store the peeked value.

Returns

true if a value was available, false otherwise.

Implements BaseBuffer< T >.

read()

template<typename T >

bool read ( T &  result )

inlineoverridevirtual

Reads a single value from Redis directly (no local buffer). Flushes any pending writes before reading.

Parameters

result

Reference to store the read value.

Returns

true if a value was read, false otherwise.

Implements BaseBuffer< T >.

readArray()

template<typename T >

int readArray ( T  data[], int  len  )

inlineoverridevirtual

Reads multiple values from the buffer in one batch. Flushes any pending writes before reading.

Parameters

data	Array to store the read values.
len	Maximum number of values to read.

Returns

Number of values actually read.

Reimplemented from BaseBuffer< T >.

readResponse()

template<typename T >

RedisResult readResponse ( )

inlineprotected

Reads a single line response from the Redis server and parses it into a RedisResult.

Returns

RedisResult structure with parsed response.

this is a length prefix line

Remove any leading or trailing whitespace

redisCommand()

template<typename T >

String redisCommand ( const String &  cmd, const String &  arg1 = "", const String &  arg2 = "", const String &  arg3 = ""  )

inlineprotected

Constructs a Redis command in RESP format.

Parameters

cmd	Redis command (e.g., "RPUSH").
arg1	First argument.
arg2	Second argument.
arg3	Third argument.

Returns

Command string in RESP format.

reset()

template<typename T >

void reset ( )

inlineoverridevirtual

Clears the buffer both locally and on the Redis server. Flushes any pending writes before clearing.

Implements BaseBuffer< T >.

resize()

template<typename T >

bool resize ( int  size )

inlineoverridevirtual

Resizes the maximum buffer size. This operation is only allowed before any write has occurred.

Parameters

size	New maximum size.

Returns

true if resized, false if any write has already occurred.

Reimplemented from BaseBuffer< T >.

sendCommand()

template<typename T >

RedisResult sendCommand ( const String &  cmd )

inlineprotected

Sends a command to the Redis server and returns the parsed result.

Parameters

cmd	Command string in RESP format.

Returns

RedisResult structure with parsed response.

setExpire()

template<typename T >

void setExpire ( int  seconds )

inline

Sets the expiration time (in seconds) for the Redis key. The expiration will be refreshed on every write/flush.

Parameters

seconds

Expiration time in seconds (0 = no expiration).

size()

template<typename T >

size_t size ( )

inlineoverridevirtual

Returns the maximum capacity of the buffer.

Returns

Maximum number of elements.

Implements BaseBuffer< T >.

write()

template<typename T >

bool write ( T  data )

inlineoverridevirtual

Buffers a single value for writing to Redis. Data is only sent to Redis when the local buffer is full or writeArray is called.

Parameters

data	Value to write.

Returns

true if buffered successfully.

Implements BaseBuffer< T >.

writeArray()

template<typename T >

int writeArray ( const T  data[], int  len  )

inlineoverridevirtual

Writes multiple values to Redis in one batch. Flushes any pending writes before sending the new data.

Parameters

data	Array of values to write.
len	Number of values to write.

Returns

Number of values written.

Reimplemented from BaseBuffer< T >.

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The documentation for this class was generated from the following file:

• src/AudioTools/Communication/RedisBuffer.h