UT_Interrupt.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_Interrupt.h (C++)
 *
 * COMMENTS:
 *
 */

#ifndef __UT_Interrupt__
#define __UT_Interrupt__

#include "UT_API.h"

#include "UT_Array.h"
#include "UT_Lock.h"
#include "UT_SharedMem.h"
#include "UT_Signal.h"
#include "UT_StringHolder.h"
#include "UT_ThreadSpecificValue.h"
#include "UT_TimeGate.h"
#include <SYS/SYS_Compiler.h>
#include <SYS/SYS_Deprecated.h>

#include <sys/types.h>

class UT_Interrupt;
class UT_InterruptMessage;

typedef void    (*UT_InterruptCB)(UT_Interrupt *me, int state, const char *op);
typedef void    (*OPUI_UpdateModeCB)();
typedef bool    (*UI_CheckForEscapeCB)();

typedef UT_StringHolder (*UT_InterruptMessageCB)(const UT_InterruptMessage *me);

/// An intentionally light weight class to hold interrupt messages
/// The idea is people can format them with their callback methods.
/// This isn't virtual as we want to build an array of them by value
/// at this level.
/// You should harden any info you need.  Do not rely on your callback
/// being invoked in your thread or during your scope!
class UT_API UT_InterruptMessage
{
public:
    UT_InterruptMessage() { myBuildMessageCallback = 0; }
    UT_InterruptMessage(UT_InterruptMessageCB cb) { myBuildMessageCallback = cb; }
    UT_InterruptMessage(UT_InterruptMessageCB cb, const UT_StringHolder &str) { myBuildMessageCallback = cb; myText = str; }

    const UT_StringHolder       &buildMessage() const
    {
        if (myCachedText.isstring()) return myCachedText;
        if (!myBuildMessageCallback) return myCachedText;
        myCachedText = myBuildMessageCallback(this);
        return myCachedText;
    }

private:
    mutable UT_StringHolder     myCachedText;
    UT_InterruptMessageCB       myBuildMessageCallback;

    // These are public so the callbacks can use them.
public:
    UT_StringHolder             myText;

    // We have our values.  Intentionally *not* including
    // pointers since there is no destructor and no scope.
    // The point of this is to be *fast*.
    union {
        int             i;
        float           d;
    } value1;
    union {
        int             i;
        float           d;
    } value2;
    union {
        int             i;
        float           d;
    } value3;
    union {
        int             i;
        float           d;
    } value4;
};

class UT_API UT_InterruptHandler
{
public:
    UT_InterruptHandler() = default;
    virtual ~UT_InterruptHandler() = default;

    UT_InterruptHandler(const UT_InterruptHandler &) = delete;
    UT_InterruptHandler &operator=(const UT_InterruptHandler &) = delete;

    virtual void        start(UT_Interrupt *intr,
                              const UT_InterruptMessage &msg,
                              const UT_StringRef &main_optext,
                              int priority) =0;
    virtual void        push(UT_Interrupt *intr,
                              const UT_InterruptMessage &msg,
                              const UT_StringRef &main_optext,
                              int priority) =0;
    virtual void        busyCheck(bool interrupted,
                                  float percent,
                                  float longpercent) = 0;
    virtual void        pop() =0;
    virtual void        stop() =0;

    virtual void        interruptAllowed(bool allowed, bool allow_ui) =0;
};

//
// These state values are passed to the active callback:
//
enum
{
    ACTIVE_STOP,                // Final opEnd
    ACTIVE_START,               // First opStart
    ACTIVE_PUSH,                // opStart
    ACTIVE_POP,                 // opEnd
    ACTIVE_BUSY,                // opInterrupt
    ACTIVE_ALLOW_CHANGE         // myInterruptable has changed state
};


class UT_API UT_Interrupt : protected UT_SharedMem
{
public:
    /// When interrupts nest, it is not always useful to display the
    /// entire stack of interrupts.  Priority is used to control if
    /// the interrupt should be shown.
    /// 1) All PERMANENT messages are shown.
    /// 2) Only the topmost NODE is shown, provided it isn't shadowed
    /// by a PERMANENT.
    /// 3) Only the topmost TRANSIENT is shown, provided it isn't shadowed
    /// by a PERMANENT or NODE.
    /// Node cooking in Houdini uses the NODE level, so for most ad-hoc
    /// interrupt messages the TRANSIENT level is best.
    enum Priority
    {
        PRIORITY_TRANSIENT = 0,
        PRIORITY_NODE = 1,
        PRIORITY_PERMANENT = 2,
    };

    explicit UT_Interrupt(const char *app_title = 0);
            ~UT_Interrupt() override;

    // The interrupt object must be enabled for interrupts to be
    // allowed. The initial state is disabled.
    // If print_longtext is 1, then each time the "long" text is changed
    // with setLongOpText(), the text will be printed onto stdout.
    void        setEnabled(int state, int print_longtext = 0);
    bool        isEnabled() const { return (bool) myEnableFlag; }

    // This is always locked, the interface is just for compatibility.
    SYS_DEPRECATED(19.0)
    void        setUseLocks(int /*state*/) { }

    // If this flag is set to false, the idialog is started in uninterruptable
    // mode. This makes idialog basically a status display. Also, on threaded
    // UI, hitting ESC will do nothing.
    //
    // setInterruptable(true) returns false if UT_Interrupt was already
    // interrupted, and hence will fail to turn off the interruptable flag. If
    // prev_enabled is non-nullptr, then it is set to the previous flag state,
    // regardless of the return value.
    // NB: setInterruptable() will perform locking using myInterruptableLock.
    bool        setInterruptable(bool allow, bool *prev_enabled = nullptr,
                                 bool allow_ui = false);
    bool        getInterruptable() const        { return myInterruptable; }
    UT_Lock &   getInterruptableLock()          { return myInterruptableLock; }
    bool        getAllowUI() const              { return myAllowUI; }

    // Normally the myInterruptedFlag is reset as soon as the outermost
    // opStart/opEnd pair is closed.  This does not work very well
    // if we need to track the interrupt flag across returning into
    // the event loop.  Similarly, we may wish to leave the interrupt
    // in a sticky state until someone manually re-enables cooking.
    // clearStickyInterrupts() will both clear the sticky interrupt
    // flag *AND* clear the interrupt flag.
    void        clearStickyInterrupts();
    bool        stickyInterrupts() const { return myInterruptSticky; }
    void        setStickyInterrupts();

    int         getOpDepth() const { return myOpDepth; }

    /// To use the long operation mechanism invoke "opStart" once,
    /// giving the name of the operation and (if possible) an estimate
    /// of the number of calls which are planned to be made to the
    /// opInterrupt method. The start method will return zero if the
    /// operation has already been terminated (possibly from a containing long
    /// operation) and should not even start. In that case, you *must* still
    /// call opEnd(). It will return one if the operation can proceed normally.
    ///
    /// During the long operation, invoke the "opInterrupt" method
    /// (if possible, giving a value between 0 and 100 indicating the
    /// percentage of the operation that is complete). This method will
    /// return zero if the operation should continue and one if a request
    /// was made to terminate. When the operation is complete, invoke the
    /// "opEnd" method. This should be called even if the operation was
    /// interrupted.
    ///
    /// The 'immediate_dialog' flag causes the idialog program to be started
    /// immediately instead of waiting for a timeout. This is the only way to
    /// start the idialog progress monitor, and should only be used for very
    /// long operations where the user would minimize Houdini (like rendering)
    ///
    /// The opid can be used to verify nesting of interrupts.  It can be
    /// passed to opEnd to verify that the nesting is proper...
    ///
    /// These methods are now thread safe. Only the main thread will start
    /// the interrupt server.
    // @{
    int          opStart(const char *opname = 0, int npoll = 0,
                         int immediate_dialog=0, int *opid=0);
    int          opStartPriority(int priority, const char *opname = 0, int npoll = 0,
                         int immediate_dialog=0, int *opid=0);
    int          opStartMessage(int priority, const UT_InterruptMessage &msg, int immediate_dialog = 0, int *opid = 0);

    int          opInterrupt(int percent = -1);

    void         opEnd(int opid=-1);
    // @}

    /// Call this before a new set of opStart()s are called. It will also
    /// cause idialog to configure the user interface with two text boxes
    /// instead of the usual single line. After that, you can call
    /// setLongOpText() to modify the second line message.
    // @{
    void         setLongOpText(const UT_StringHolder &longoptext);
    void         setLongPercent(float percent);
    // @}

    // The application title string will be placed in the percent
    // completion dialog.
    void         setAppTitle(const char *title);
    UT_StringHolder getAppTitle() const { return myAppTitle; }

    // The active callback is invoked whenever opStart and opEnd are called.
    // This lets someone else keep track of when we're inside an interruptible
    // loop. The Interrupt Handler is similar but C++ based.
    void         setActiveCallback(UT_InterruptCB function)
                 { myActiveCallback = function; }

    void         setInterruptHandler(UT_InterruptHandler *hand)
                 {
                     myUIHandler = hand;
                     if(hand)
                         hand->interruptAllowed(myInterruptable, myAllowUI);
                 }
    UT_InterruptHandler *getInterruptHandler() { return myUIHandler; }

    // Set the 'ourMemoryThresholdCallback' ptr to 'function'. See the
    // declaration of ourMemoryThresholdCallback for more details.
    static void  setUpdateModeCallback(OPUI_UpdateModeCB function)
                 { ourMemoryThresholdCallback  = function; }

    // Set the 'ourEscapeCheckCallback' ptr to 'function'.  See the
    // declaration of ourEscapeCheckCallback for more details
    static void  setEscapeCheckCallback(UI_CheckForEscapeCB function)
                 { ourEscapeCheckCallback  = function; }
    static bool  getIsEscapeCheckCallbackSet()
                 { return ourEscapeCheckCallback; }

    // The interrupt callbacks are called when the user interrupts Houdini.
    // Add an interrupt callback when the operation being called needs to
    // do extra work to interrupt the main thread.  For example, to stop
    // python execution, an interrupt callback is needed to raise a python
    // exception.
    //
    // Only the callback that was pushed last will be called.
    void         pushInterruptCallback(void (*callback)());
    void         popInterruptCallback();

    // You can manually interrupt an active loop by calling this method.
    // use_semaphore is ignored, this will always lock.
    SYS_DEPRECATED(19.0)
    void         interrupt(int /*use_semaphore*/) { interrupt(); }
    void         interrupt();

    void         pause(bool dopause);

    bool         isPaused() const;

    // This is the signal handler that gets used when we're not in an
    // interruptable state.
    void         setSignalCallback(UTsigHandler function);

    // test if we're within the memory threshold, and if not, return true.
    bool         testMemoryThreshold()
                 {
                     return ourMemoryThresholdCallback
                                ?  doTestMemoryThreshold() : false;
                 }

    /// We have some hystersis from starting a computation and accepting
    /// the first interrupt, this avoids interactive computations from
    /// suddenly getting interrupted by escape keys.
    bool         readyForInterrupts() const
    {
        return myReadyForInterrupts.canAcquire();
    }

    /// Resets the ready for interrupt so no interrupts will be triggered
    /// until the hystersis interval (~200ms) occurs
    void          delayNextInterrupt()
    {
        myReadyForInterrupts.acquire();
    }

protected:
    // These methods are used by the interrupt server to get access
    // to the shared memory segment.
    const char          *getSharedKey() const;

private:
    bool                 doTestMemoryThreshold();
    void                 testIdialogInterrupt();
    void                 testEscCallbackInterrupt();

    void                 updateTitle(const char *title);
    void                 operationComplete();
    void                 startServer();
    void                 stopServer();
    UT_StringHolder      getOpName() const;
    void                 callInterruptCB();


    UT_Array<UT_InterruptMessage>        myOpNameStack;

    UT_Array<void(*)()> myInterruptCBStack;

    UT_StringHolder      myAppTitle;
    UT_StringHolder      myLongOpText;
    UT_InterruptCB       myActiveCallback;
    UT_InterruptHandler *myUIHandler;
    UT_StringHolder      myServerPath;
    int                  myOpDepth;
    UT_Interrupt        *myPreviousInterrupt;
    UT_Signal           *mySignal;
    UT_Signal           *mySignalSubstitute;
    UTsigHandler         mySignalCallback;
    pid_t                myServerPID;

    int                  myStartTime;

    unsigned char        myEnableFlag;          // Interrupts currently enabled
    unsigned char        myEverEnableFlag;      // Have they ever been enabled?
    short                myStartedFlag;
    short                myInterruptedFlag;
    char                 myPrintLongTextFlag;
    bool                 myInterruptable;
    bool                 myAllowUI;
    bool                 myInterruptSticky;
    float                myPercent;
    float                myLongPercent;
    volatile bool        myPaused;

    UT_ThreadSpecificValue<int> myTLSDepth;

    // This is how we let OPUI_App know we'd like to change the update mode
    // to OPUI_UPDATE_ON_DEMAND when we're running out of virtual addresses
    static OPUI_UpdateModeCB     ourMemoryThresholdCallback;

    // This is how we ask the UI layer to check whether an escape key has
    // been pressed in the case where we do not have threaded UI.
    static UI_CheckForEscapeCB   ourEscapeCheckCallback;

    UT_Lock              myLock;
    UT_Lock              myInterruptableLock;

    UT_TimeGate<100>     myTimeGate;
    UT_TimeGateD         myReadyForInterrupts;

    static void          ut_interruptHandler(UTsignalHandlerArg);
};

/// Obtain global UT_Interrupt singleton.
UT_API extern UT_Interrupt      *UTgetInterrupt();
UT_API extern void               UTsetInterrupt(UT_Interrupt *);

// a template for the comm layout for the shared memory link between
// UT_Interrupt and idialog.
struct ut_InterruptTransactionData
{
                                        // I/O is relative to UT_Interrupt.
    volatile int   myCommand;           // In: 0 none, 1 interrupt, 2 pause
    volatile float myPercent;           // Out: current task % complete
    volatile float myLongPercent;       // Out: primary task % complete
    volatile int   myNumMessages;       // Out: # of messages in message area
    volatile char  myMessage[128];      // Out: message
    volatile char  myLongMessage[128];  // Out: message for long ops
};

// A simple client which can be used in processes spawned by Houdini (such
// as mantra). It allows these processes to report the completion percentage,
// and read the interrupt/pause state.
class UT_API UT_InterruptClient : public UT_SharedMem
{
public:
     UT_InterruptClient();
    ~UT_InterruptClient() override;

    bool        isValid();

    bool        isInterrupted();

    void        setPercent(float p);
    void        setLongPercent(float p);

    void        setMessage(const char *title);
};

/// Helper class to ensure that opEnd() is always called, even if you
/// return early from a function. It's similar to UT_AutoUndoBlock.
class SYS_NO_DISCARD_RESULT UT_AutoInterrupt
{
public:
    UT_AutoInterrupt(const char* operation_name,
                     UT_Interrupt::Priority priority,
                     UT_Interrupt *boss=UTgetInterrupt())
        : myInterrupt(boss)
    {
        myRunOk = myInterrupt
            ? (bool)myInterrupt->opStartPriority(priority, operation_name,
                                                 0, 0, &myId)
            : true;
    }

    UT_AutoInterrupt(const char* operation_name,
                     UT_Interrupt *boss=UTgetInterrupt())
        : myInterrupt(boss)
    {
        myRunOk = myInterrupt
            ? (bool)myInterrupt->opStart(operation_name, 0, 0, &myId)
            : true;
    }

    ~UT_AutoInterrupt()
    {
        if (myInterrupt)
            myInterrupt->opEnd(myId);
    }

    bool wasInterrupted()
    {
        if (myRunOk && myInterrupt && myInterrupt->opInterrupt())
            myRunOk = false;
        return !myRunOk;
    }

    bool wasInterrupted(int percent)
    {
        if (myRunOk && myInterrupt && myInterrupt->opInterrupt(percent))
            myRunOk = false;
        return !myRunOk;
    }

    UT_Interrupt        *getInterrupt() const   { return myInterrupt; }

private:
    UT_Interrupt        *myInterrupt;
    bool                 myRunOk;
    int                  myId;
};

#endif /* __UT_Interrupt__ */