Implemented history writer
This commit is contained in:
Martino Ferrari
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/**
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* @file HistoryWriter.h
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* @brief Disk-backed circular history storage for StreamHub signals.
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*
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* Each signal is stored in a separate binary file (.shist) with a fixed header
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* and a pre-allocated circular data region of (float64 time, float64 value) pairs.
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* The file size is determined at creation and never grows.
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*
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* File layout (per signal):
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* Offset Size Field
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* 0 4 Magic: "SHR1"
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* 4 4 uint32 version (1)
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* 8 4 uint32 capacity (max pairs)
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* 12 4 uint32 head (next write position, 0-based, wraps)
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* 16 4 uint32 count (valid entries, <= capacity)
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* 20 4 uint32 decimation
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* 24 8 float64 tOldest
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* 32 8 float64 tNewest
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* 40 24 reserved (pad to 64 bytes)
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* 64 ... data: capacity × 16 bytes (8 time + 8 value)
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*
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* Thread safety: WriteTick() is called from the push loop only.
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* ReadRange() uses pread() and is safe for concurrent reads from WS threads.
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*/
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#ifndef STREAMHUB_HISTORY_WRITER_H_
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#define STREAMHUB_HISTORY_WRITER_H_
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#include "CompilerTypes.h"
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#include "StreamString.h"
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#include "StructuredDataI.h"
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#include "UDPSourceSession.h"
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namespace StreamHub {
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using MARTe::uint8;
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using MARTe::uint16;
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using MARTe::uint32;
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using MARTe::uint64;
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using MARTe::float64;
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using MARTe::StreamString;
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using MARTe::StructuredDataI;
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/** Maximum number of sessions (matches kMaxSessions). */
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static const uint32 kHistMaxSessions = 32u;
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/** Header size in bytes. */
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static const uint32 kHistHeaderSize = 64u;
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/** Magic bytes. */
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static const char kHistMagic[4] = {'S','H','R','1'};
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class HistoryWriter {
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public:
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HistoryWriter();
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~HistoryWriter();
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/**
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* @brief Parse +History block from StreamHub config.
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*
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* Expected keys inside a +History node:
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* Directory (string, required)
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* DurationHours (float64, default 1)
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* Decimation (uint32, default 1)
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* FlushIntervalSec (uint32, default 5)
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* MinDiskFreeMB (uint32, default 500)
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*/
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bool Initialise(StructuredDataI &cfg);
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/** @return true if history storage is enabled and initialised. */
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bool IsEnabled() const { return enabled_; }
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/**
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* @brief Called when a source becomes configured.
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* Creates / reopens per-signal .shist files.
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*/
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void OnSourceConfigured(uint32 sessionIdx, const char *sourceId,
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UDPSourceSession &sess);
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/**
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* @brief Called from the push loop to write new samples for one session.
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* Uses per-signal ReadSince cursors. Applies decimation.
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*/
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void WriteTick(uint32 sessionIdx, UDPSourceSession &sess);
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/**
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* @brief Flush in-memory header state to disk (periodic).
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*/
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void FlushHeaders();
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/**
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* @brief Read a time range for one signal from disk.
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* @return Number of (t,v) pairs written to tOut/vOut.
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*/
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uint32 ReadRange(const char *sourceId, const char *signalName,
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float64 t0, float64 t1,
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float64 *tOut, float64 *vOut, uint32 maxOut) const;
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/**
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* @brief Get the time range stored on disk for a signal.
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* @return true if the signal has history data.
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*/
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bool GetTimeRange(const char *sourceId, const char *signalName,
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float64 &t0, float64 &t1) const;
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/**
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* @brief Build a JSON fragment for historyInfo response.
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* Writes into buf at offset, growing via the provided append function.
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*/
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void AppendInfoJSON(char *&buf, uint32 &off, uint32 &cap) const;
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/** @brief Check available disk space. */
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bool HasSufficientDisk() const;
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/** @brief Duration in hours. */
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float64 DurationHours() const { return durationHours_; }
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/** @brief Decimation factor. */
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uint32 Decimation() const { return decimation_; }
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private:
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struct SignalFile {
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int fd; /**< File descriptor (-1 = not open) */
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uint32 capacity; /**< Total capacity in pairs */
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uint32 head; /**< Next write position */
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uint32 count; /**< Valid entries */
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float64 tOldest;
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float64 tNewest;
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uint64 readCursor; /**< For ReadSince from ring buffer */
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uint64 decimCounter; /**< Decimation sample counter */
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bool headerDirty; /**< True if header needs flushing */
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char sourceId[64]; /**< Source ID for lookup */
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char signalName[64]; /**< Signal name for lookup */
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};
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/** Per-signal scratch for reading from rings. */
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static const uint32 kReadScratch = 65536u;
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float64 *scratchT_;
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float64 *scratchV_;
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/** Maximum signals tracked per session for history. */
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static const uint32 kHistMaxSignals = 64u;
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/** Heap-allocated to keep StreamHub object size manageable. */
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SignalFile (*files_)[kHistMaxSignals]; /**< [kHistMaxSessions][kHistMaxSignals] */
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bool (*fileActive_)[kHistMaxSignals]; /**< [kHistMaxSessions][kHistMaxSignals] */
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bool enabled_;
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char directory_[512];
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float64 durationHours_;
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uint32 decimation_;
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uint32 flushIntervalSec_;
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uint32 minDiskFreeMB_;
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bool diskLow_; /**< True when disk space is below threshold */
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/** Create or reopen a .shist file for one signal. */
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bool OpenSignalFile(uint32 sessionIdx, uint32 sigIdx,
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const char *sourceId, const char *signalName,
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float64 estimatedRateHz);
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/** Write a batch of (t,v) pairs to a signal file. */
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void WritePairs(SignalFile &sf, const float64 *t, const float64 *v,
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uint32 n);
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/** Flush one signal file header to disk. */
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void FlushHeader(SignalFile &sf);
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/** Find a signal file by sourceId:signalName. */
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const SignalFile* FindFile(const char *sourceId, const char *signalName) const;
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};
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} /* namespace StreamHub */
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#endif /* STREAMHUB_HISTORY_WRITER_H_ */
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