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frog707 · 6 months ago

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Mystery solved

I believe I've solved the mysterious/scary bug I blogged about yesterday.

Last week I tried to eliminate some repeated code by turning it into "inline" methods that return references to objects. I changed code like this (simplified for clarity):

float getForceX(jlong bodyVa) { Body *pBody = reinterpret_cast<Body *> (bodyVa); const Vec3& result = pBody->GetForce(); return vec3.GetX(); } float getForceY(jlong bodyVa) { Body *pBody = reinterpret_cast<Body *> (bodyVa); const Vec3& result = pBody->GetForce(); return vec3.GetY(); } float getForceZ(jlong bodyVa) { Body *pBody = reinterpret_cast<Body *> (bodyVa); const Vec3& result = pBody->GetForce(); return vec3.GetZ(); }

into code like this (also simplified):

inline const Vec3& getF(jlong bodyVa) { Body *pBody = reinterpret_cast<Body *> (bodyVa); const Vec3& result = pBody->GetForce(); return result; }

float getForceX(jlong bodyVa) { const Vec3& vec3 = getF(bodyVa); return vec3.GetX(); } float getForceY(jlong bodyVa) { const Vec3& vec3 = getF(bodyVa); return vec3.GetY(); } float getForceZ(jlong bodyVa) { const Vec3& vec3 = getF(bodyVa); return vec3.GetZ(); }

In the back of my mind, I assumed Body::GetForce() was returning a reference to a Vec3, so it made sense for getF() to do likewise. But in fact, Body::getForce() returns a copy of a Vec3. Because of this, the compiler allocated stack space for a copy, then returned a reference to that copy. But the copy is only live during execution of getF(). Once the function returns, the copy can (and does) get trashed.

The correct solution, I think, is for getF() to likewise return a copy:

inline static const Vec3 getF(jlong bodyVa) { Body *pBody = reinterpret_cast<Body *> (bodyVa); const Vec3 result = pBody->GetForce(); return result; }

Two little ampersands can make a big difference!

This bug illustrates a couple subtle differences between C++ and Java. In Java, objects are passed and returned by reference, never by copy, so the latter possibility didn't occur to me. Furthermore, Java objects live on a heap, not a stack; as long as a reference lives, objects don't get trashed. Upshot: I'm out of practice thinking about this sort of issue.

Part of what made the bug hard to find was that it only caused failures when optimization was turned on. For various reasons, most of my testing is done with optimization turned off.

I'm not 100% sure how compiler optimization surfaced this bug, but I have some ideas. I could disassemble the compiled code, but I'm not curious enough to do that today.

The interesting question is: how does one solve a bug like this? I wish I'd used some clever tools or techniques, which I could now recommend. In fact, I solved it by trial and error, and my only relevant advice is to be persistent.

#software development #software bugs #war stories #c++#java #troubleshooting #debugging #vectors #heap #coding #persistence #trial and error #ampersand #compiler #reference #advice

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gyrlversion · 5 years ago

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CYNTOIA BROWN SIMILAR STORY ............................................................ #cyntoiabrown isn't the only female victim nit given justice by the system. #chrystulkizer is facing life for killing a man who forced child pornography and raped her repeatedly .... #freechrystulkizer . . . #gyrlversion #cyntoia #jlong https://www.instagram.com/p/B1AYn_hAVCU/?igshid=1r9yap1horr9n

#cyntoiabrown #chrystulkizer #freechrystulkizer #gyrlversion #cyntoia #jlong

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sweaterangst · 2 years ago

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i watched barbarian last weekend btw and i can feel the demons whispering

#my jlong phase coming back despite his absolutely reprehensible character in that movie #its so good btw!!!! god i love seeing justin in horror SO much!!!#everybody is so lucky i have a job now btw. lest i subject u all to jlong phase 2 electric boogaloo

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declinerewind · 3 years ago

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* / THIS FEELS TOO GOOD TO LET GO !

♡ . jlong & sunmi !

now playing ... deathwish by stand atlantic !

𝐢. THE FIRST TIME sunmi almost kissed jiaolong, she had been eighteen years old and he had just saved her from nearly getting run over by a semi. the camera crew of sbs' roommates were just feet away capturing the wholesome moment between the cyno member and former luv member, but all she could focus on was the feeling of his chest pressed against her back, his arms keeping her between him and the entry of the alleyway, safe from the truck , and the way her heart was hammering away in her chest.

she'd been teasing him not two minutes ago, something about his height just to get on his nerves ( as she usually did ) and he had playing it up for cameras for a moment before jiaolong had spotted the semi always more spacially aware than her speeding towards them. the world had slowed as her grabbed her by her oversized hoodies and pulled her towards him, the former idol becoming increasingly aware of how close she was to her long time friend as her heart crawled up into her throat.

she could remember looking up to glance a him, only to find him already looking at her. the way her cheeks had heated up was immediate, as was the way her eyes had briefly landed on his plush lips, an intrusive curiousity about how his lips would feel against hers worming it's way into her brain. but it was gone as quickly as it came, the presence of the cameras suddenly weighing a tonne. jiaolong, not noticing her sudden change in demeanor, would then go on to teasingly ( but gently ! ) shove her away from her like nothing had happened before carrying on with their mission.

she must have a death wish of some kind ... how annoying.

now playing ... life was easier when i only cared about me by bad suns !

𝐢𝐢. THE SMELL OF POLLEN and the appearance of a bouquet of beautiful, blooming bleeding hearts, cherry blossoms and water lillies ( her three favourite flowers ever how had he known ? ) outstretched towards her had been the cause of the second almost kiss on her behalf. the backstage area of all stars was in chaos, families running around either to congratulate the winners ( her future group mates ... her guilt about what had happened to luv still made that thought weigh heavily on her slim shoulders ) or comfort those who hadn't passed the final round her own parents were no where to be seen, but she hadn't expected them to show up to congrulate her on making it. they had never cared about her unless she was giving them her hard earned money, anyways but the last thing she had expected was for jiaolong to show up instead, and with a bouquet of her favourite flowers to boot.

her throat had closed up at the sight before her, the intrusive realisation of maybe she didn't have to always be alone arriving quickly at his appearance maybe she really did want someone there to tell her she had worked hard, that she had done a good job. exhaling shakily, small hands extending to take the bouquet from her as the realisation that she was finally redebuting hit her, the weight settling between her shoulder blades and resting against her sore neck; she would bring the bouquet towards her, hugging it gently against her aching chest and burying her nose in the petals as jiaolong voiced his pride fresh tears pricking against her already swollen eyes at his words.

looking back up at him, the way he was looking at her, with pride all but dripping from his honey eyes, she was struck with yet another realisation; that jiaolong had been there for her through everything. he had been there when luv had been forced to disband, he had been there her parents had shown up, demanding money a mere week after said disbandment, and he had been there when she finally snapped and screamed at them until they ran from the prism building and never came back. he had been through everything, and he had taken her teasing and sarcastic comments in his stride all because he cared for her.

he had always cared for her so openly that it made her chest physically ache. she didn't deserve his kindness in the slightest and yet he was still here, congratulating her for her hard work and singing praises like she deserved them. her heart ached with something new, and unfamiliar as she watched him she didn't know if it was love, but the sensation was enough to spur her forward so that she could wrap her arms around his wide shoulders. a kiss would have ruined the moment, and a hug felt too intimate but the moment he wrapped his arms around her waist in return as she whispered her gratitude for him being there, she knew he felt like home.

now playing ... pretty please by jackson wang !

𝐢𝐢𝐢. RAUCOUS�� LAUGHTER FILLS fills the room as sunmi watches with fond eyes as jiaolong spins his mother around, continuing their dance as the song you who sat next to me by gao xiaosong flowed into the air from the old record player that sat in the corner of the room. the brunette, now aged twenty years old, had since gotten used to the way her heart would flutter and clench uncomfortably whenever her best friend looked over at her with those dangerous, honey brown eyes of his, but what she hadn't gotten used to was the way in which his endearing mother ( who had always treated sunmi as her own child ) had stopped referring to sunmi as jiaolong's best friend and had instead taken to asking her when she and her son were planning on getting married.

he absolutely didn't help the situation either, mind you. in fact, jiaolong would smile deviously at her and repeat his mother's question as if to tease her, give her a taste of her own medicine when he knew she was defenceless against his kind mother. sunmi was sure he was blind to the way she would flush a soft red as well, which only made it worse for her.

the soft tones of gao xiaosong would slowly but surely fade into the next song on the record, the wen matriarch pulling her beloved son into a tight hug before she waddled off towards the kitchen to start dinner but not before reaching out to briefly hold sunmi's hand on her way past. too distracted by her thoughts, the idol would fail to notice jiaolong's presence until he fell onto the couch beside her, nudging her knee with his own, causing her too look over at him and god, how she wished she hadn't. the white dress shirt had become dishevelled during his dance with his mother, the three top buttons were undone allowing the tanned skin of his chest and collarbones to peek though, his black hair was pushed away from his face, slightly flushed red and his lips parted slightly, and his legs were clad in black dress pants and ... she suddenly needed to get out of there very, very quickly.

unfortunately for her, any and all escape options went out the window when the man beside her held out a large, calloused hand towards her and her heart jumped into her throat. she could recall staring at him like he'd grown a second head, determined to keep her calm façade and raising an eyebrow, " what ? " she had asked and he had laughed, taking her hand into his own pulling her up alongside him. " dance with me. "

he laughed once more as she rolled her eyes at him, a sound that usually brought sunmi great comfort but, under the current circumstances where she could feel his laughter rumbling against her chest as if it was her own, it only made it harder for her to not kiss him. so instead, as he wrapped muscular arm around her waist, she gripped his forearm, looked up at him and smirked like she was fine, " fine. but don't step on my feet. "

now playing ... soulmate by zico & iu !

𝐢. DECEMBER 25, 2019, a fresh blanket of snow covered the streets of seoul, the same it always did on the anniversary of yeun sunmi's birthday. ice clung desperately to every inch of the newly turned twenty two year old's covered body, silver particles dusting her hair and causing her nose and cheeks to glow an embarrassingly red colour. but if you peered a few inches downwards, you would notice the red colour that accentuated her earth toned eyes had absolutely nothing to do with the cold.

for in her gloved palm sat a crystal known as a rose quartz; the precious stone that represented unconditional love. tears pricked at her eyes, desperate to escape at the heavy meaning this little rock carried within it, and she was so highly aware of the way jiaolong was watching her, patiently waiting for her to say something but how could she ? how could she when he had just essentially given her a rock that served as both a confession and a promise to love her unconditionally. she had always known that he felt the same way about her that she did him to a certain degree, hell, he had practically sung about it any chance he got, but for some reason, the crystal sitting in her hand made it that much more real.

finally, she would look up at him with tears still decorating her waterline, uncertainty clear in her eyes as she glanced between him and the precious stone in her palm, " do ... do you " her voice broke pathetically, but she carried on despite it. " do you know what rose quartz means ? " please say yes, please say yes, her mind begged as she watched him. jiaolong seemed to pause, thinking of his response before he nodded slowly as he shoved his hands into the pockets of his jacket, speaking after the brief moment of silence,�� " unconditional love, right ? ... also means you can't get rid of me. "

taking a moment to gently pocket the preciouspreciousprecious stone, this time, sunmi wouldn't stop herself from surging forward to finally press her cold lips against his own just as every bit of adoration, admiration, and love she felt for him finally broke through the dam she had built around her heart. pulling away a moment later, the idol wasn't able to stop the gentle sob that escaped her as she ( lightly ! ) hit his chest over and over she didn't deserve him, not even in the slightest, and yet there he was, as always. steadfast and unmoving in his belief and loyalty in her. " you're such an idiot, " she whispered against the chilly december winds, looking up at him once more before she moved to wrap her arms around his reliable shoulders once more. " why would i ever want to get rid of you ? "

now playing ... moonlight by twice !

𝐞𝐩𝐢𝐥𝐨𝐠𝐮𝐞. IF YOU OPENED into the bottom drawer of sunmi's bedside table though she isn't sure why you would you would surely found a journal that, at first sight, wasn't anything to get excited about, but the inside ? oh, the inside held stories of romance and love that words alone could never even hope to describe.

pressed flowers upon pressed flowers, the dried petals of every single bouquet jiaolong had ever gotten her; starting with the one he gave her after she got into cherie seven years ago to the one he had given to her the other week for no reason other than he loved her. carefully taped in polaroids that ranged in age and quality but always showed the same things; jiaolong on his own or the pair together. as well as every hand written note he had left for her since they had started dating, some longer than others and some short, but each penned word was undoubtedly dipped in tooth rotting levels of sweetness from his pure adoration for her.

so, where was the rose quartz he gifted her, you may ask ? sunmi had the crystal carefully tied to a custom made chain for her phone as to ensure the small but meaningful gemstone could go with her everywhere. it can be spotted in most of her mirror selfies, taking pride of place against her phone and hand, almost as though jiaolong was right there with her ... even ( and especially ) when he can't be there in person.

#blurbs.#jlong & sunmi.#this was so sosososo much fun to write god #i love them sm #sunmi setimental queen #yeun sunmi.

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bizarrescribblez · 2 years ago

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omg dw abt rbing my jlong stuff, its not a bother at all 8w8 i actually really enjoy reading ur tags whenever u rb my posts!!! its so hard finding other justin fans sometimes ajfbjsdbjsjd

OMGGG HI HELLO!!! 🥺🥺 AA IM SO GLAD OH MYGOSH 😭 I was like “omg I hope im not coming off annoying or weird..” LIKE FR GLAD YOU ENJOY MY TAGS!! I hope you know that your Wallace art FR FR is my absolute favorite ever like literally made me more obsessed with Tusk/him in general!! AND I HOPE YOU FR KNOW YOU KICKSTARTED ME ADDING MORE OF HIS MOVIES TO MY WATCHLIST!! Like I wanna watch that Die Hard movie hes in so bad cuz 1) he looks so loser in it and 2) it was actually playing at the toy store in my town the other day and I saw him and knew I needed to see it asap.

#📫 ask box!#ONCE AGAIN IM SO GLAD IM NOT ANNOYING OMG #you FR made my Justin brainrot increase (affectionately)

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castielhasabigdick · 2 years ago

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not to make everything about jackles but I think jlong >>> jick

#jhlong maybe?#w.txt

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goatedgreen · 3 years ago

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jell jeah jental jillness jets jgo - jeans anon i am so sorry GHJKBGHJK

its okay janon, sometimes we need an outlet to have a jeans related convo and im glad my ask box was what you needed <3 jive jlong jand jrosper

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weyoun · 6 years ago

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@critical-misfit

found in a thrift store in Oklahoma

#us #fashion #jeans #its a jirt #or a jlong jleeve

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aptronyms · 5 years ago

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jlongs

no idea what this means but good for u :)

#neon.txt #asks

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verumluxs · 5 years ago

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❝ BECAUSE IT'S YOU // @servphics

𝐋𝐄𝐓'𝐒 𝐆𝐄𝐓 𝐎𝐍𝐄 𝐓𝐇𝐈𝐍𝐆 𝐒𝐓𝐑𝐀𝐈𝐆𝐇𝐓. akiyama hikari was a good liar, the first half of her life had made sure of that, but lying to her boyfriend ? that was apparently where her acting abilities stopped. the plan had been hatched over two months ago during a conversation between the cyno members sans aforementioned boyfriend where the other members were telling the maknae about how much seojin apparently missed her despite him never admitting to it outloud. how typical, she had thought as she watched the absolute o n s l a u g h t of messages that appeared in the chatroom, only chiming in when necessary.

hiding the fact that she was coming to surprise him during their tour was undoubtedly one of the hardest things she had ever done, ignoring his texts and calls ? now that was something else entirely. every time he called or messaged her, hikari could feel a pot of guilt opening in her stomach — she just prayed that he wouldn't be too mad when she eventually showed up right in front of him. walking through the hotel lobby, the brunette couldn't help but think about how similiar all this was to those one direction fanfictions she had read in her youth, a smile appearing on her face at the thought as she entered the elevator, hitting the button that read 19th floor as she did.

at this point, the butterflies in her stomach were completely undeniable, her fingers tapped anxiously on her thigh as she waited for the doors to open. jumping slightly when they did, the maknae would move to exit the elevator all whilst pulling out her phone to check the message from ryuusuke which held seojin's room number along with a hurried message that read ' please hurry, he might actually kill us ' in japanese — a sight that made her smile slightly — before she tucks her phone away and heads towards the room.

opening the door which has previously been open just a crack, the young dancer would barely be able to hold back her laughter at the sight of seojin, ryuu and jlong all sitting in the room, the latter two clearly attempting to distract her partner by playing a rather violent round of street fighter. quietly placing her suitcase down, the brunette would move up behind the couch before leaning down and wrapping her arms around seojin's shoulders, resting her chin on his head. " mind if i play a game ? i haven't played street fighter in ages. "

#the babies !!!#* 03. 𝘼𝙆𝙄𝙔𝘼𝙈𝘼 𝙃𝙄𝙆𝘼𝙍𝙄 › 𝘛𝘏𝘙𝘌𝘈𝘋𝘚 #* 06. 𝘼𝙆𝙄𝙔𝘼𝙈𝘼 𝙃𝙄𝙆𝘼𝙍𝙄 › 𝘈𝘏𝘕 𝘚𝘌𝘖𝘑𝘐𝘕

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